{"product_id":"caplugs-300-2916-020-ldpe-test-tube-stopper-16mm-natural","title":"Test Tube Stoppers, LDPE, Natural — 300-2916-020 | 1000\/Bag | Caplugs® Evergreen","description":"\u003ch2\u003eTest Tube Stopper Caps for 16 mm Test Tubes, LDPE, Natural — 300-2916-020 | 1000\/Bag\u003c\/h2\u003e \u003ctable\u003e \u003cthead\u003e\u003ctr\u003e\u003cth colspan=\"2\"\u003eQuick Reference — 300-2916-020\u003c\/th\u003e\u003c\/tr\u003e\u003c\/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eTube OD\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003e16 mm\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eCap Type\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003eStopper (plug-in friction fit)\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003eLow-Density Polyethylene (LDPE)\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eColor\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003eNatural\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eTube Types\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003e16 × 100 mm\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eTemp Range\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003e-20°C to +60°C (LDPE flex range)\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003eSterility\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003eNon-Sterile\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003ePack Size\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003e1000 \/ Bag\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003e\u003cstrong\u003ePrice\u003c\/strong\u003e\u003c\/td\u003e \u003ctd\u003e$66.96 \/ Bag ($0.0670 \/ stopper)\u003c\/td\u003e \u003c\/tr\u003e \u003c\/tbody\u003e \u003c\/table\u003e \u003ch2\u003eTechnical Narrative\u003c\/h2\u003e \u003cp\u003eThe Caplugs® Evergreen is a natural LDPE stopper cap for 16 mm OD test tubes — designed for 16 mm OD test tubes used in clinical chemistry, serology, and large-format culture tube workflows. The 16 mm stopper serves large-format clinical chemistry, serology, and culture tube workflows. Natural LDPE stoppers are the all-purpose default for 16 mm tubes, compatible with any labeling method and suitable for universal tube workflows.\u003c\/p\u003e \u003cp\u003eLDPE's low-density flex modulus provides the compression and spring-back required for friction-fit stopper retention across repeated insertion\/removal cycles — the property that makes LDPE the only appropriate material for stopper-style tube caps. LDPE retains flexibility from -20°C through 60°C, preventing brittle failure during frozen archive stopper removal and maintaining seal engagement during incubation. Chemical inertness to serum, plasma, broth media, and aqueous buffers ensures no leaching into tube contents.\u003c\/p\u003e \u003cp\u003eAt $66.96 per 1000\/Bag — $0.0670 per stopper. Also available: 300-2916-R20 (Red 16 mm, $66.96); 300-2917-B2N (Blue 17 mm, $53.19).\u003c\/p\u003e \u003ch2\u003eTechnical Specifications — Caplugs® Evergreen \u003c\/h2\u003e \u003ctable\u003e \u003cthead\u003e\u003ctr\u003e \u003cth\u003eSpecification\u003c\/th\u003e \u003cth\u003eValue\u003c\/th\u003e \u003c\/tr\u003e\u003c\/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd\u003ePart Number\u003c\/td\u003e \u003ctd\u003e\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eCaplugs Item #\u003c\/td\u003e \u003ctd\u003e3002916020E1\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eTube OD\u003c\/td\u003e \u003ctd\u003e16 mm\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eCap Style\u003c\/td\u003e \u003ctd\u003eStopper — plug-in friction fit\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eMaterial\u003c\/td\u003e \u003ctd\u003eLow-Density Polyethylene (LDPE)\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eColor\u003c\/td\u003e \u003ctd\u003eNatural\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eTube Compat.\u003c\/td\u003e \u003ctd\u003e16 × 100 mm\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eTemp Range\u003c\/td\u003e \u003ctd\u003e-20°C to +60°C\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eSterility\u003c\/td\u003e \u003ctd\u003eNon-Sterile\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003ePack Size\u003c\/td\u003e \u003ctd\u003e1000 \/ Bag\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eBPA\/Phthalate\u003c\/td\u003e \u003ctd\u003eBPA-free; no phthalate plasticizers\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eCountry of Origin\u003c\/td\u003e \u003ctd\u003eMade in U.S.A. (California)\u003c\/td\u003e \u003c\/tr\u003e \u003c\/tbody\u003e \u003c\/table\u003e \u003ch2\u003eTest Tube Stopper Application Compatibility — 16 mm\u003c\/h2\u003e \u003cp\u003eThe 16 mm natural stopper fits standard 16 mm OD tubes for these workflows:\u003c\/p\u003e \u003ctable\u003e \u003cthead\u003e\u003ctr\u003e \u003cth\u003eApplication\u003c\/th\u003e \u003cth\u003eSpecimen \/ Use\u003c\/th\u003e \u003cth\u003eNotes\u003c\/th\u003e \u003c\/tr\u003e\u003c\/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd\u003eCulture tube capping\u003c\/td\u003e \u003ctd\u003eMicrobiology culture tubes, TSB, BHI, LB broth\u003c\/td\u003e \u003ctd\u003eLDPE stopper seals tube during incubation; flex retained at 37°C\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eSpecimen tube archiving\u003c\/td\u003e \u003ctd\u003eSerum, plasma, blood in refrigerated\/frozen storage\u003c\/td\u003e \u003ctd\u003ePrevents evaporation during extended cold storage\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eClinical tube color routing\u003c\/td\u003e \u003ctd\u003eCLSI-convention color stoppers for specimen-type ID\u003c\/td\u003e \u003ctd\u003eColor stop mirrors vacuum tube top-color conventions\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eCell culture tube capping\u003c\/td\u003e \u003ctd\u003eSuspension culture, virus propagation\u003c\/td\u003e \u003ctd\u003eStopper allows gas exchange while preventing contamination\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003ePneumatic tube transport\u003c\/td\u003e \u003ctd\u003eSample tube transport in clinical systems\u003c\/td\u003e \u003ctd\u003eLDPE flex retention survives transport acceleration forces\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eChemistry tube sealing\u003c\/td\u003e \u003ctd\u003ePre-analysis sample tube closure\u003c\/td\u003e \u003ctd\u003eLDPE inert to serum\/plasma; no leaching into specimen\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eResearch reagent tubes\u003c\/td\u003e \u003ctd\u003eBuffer, reagent, stock solution tube archiving\u003c\/td\u003e \u003ctd\u003eStopper seals reusable glass and PS tubes between uses\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eHematology \/ coagulation\u003c\/td\u003e \u003ctd\u003eEDTA, citrate anticoagulant tube formats\u003c\/td\u003e \u003ctd\u003eColor-coded stoppers for anticoagulant tube designation\u003c\/td\u003e \u003c\/tr\u003e \u003c\/tbody\u003e \u003c\/table\u003e \u003cp\u003e\u003cem\u003eAlways validate stopper fit with your specific tube brand — 16 mm OD tubes vary in opening diameter by wall thickness. Request a free sample before bulk purchase.\u003c\/em\u003e\u003c\/p\u003e \u003ch2\u003eChemical Resistance — Low-Density Polyethylene (LDPE)\u003c\/h2\u003e \u003cp\u003eLDPE provides flexibility for friction-fit stopper retention and inertness to clinical specimen matrices.\u003c\/p\u003e \u003ctable\u003e \u003cthead\u003e\u003ctr\u003e \u003cth\u003eReagent \/ Condition\u003c\/th\u003e \u003cth\u003eCompatibility\u003c\/th\u003e \u003c\/tr\u003e\u003c\/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd\u003eAqueous buffers \/ water\u003c\/td\u003e \u003ctd\u003e✓ Excellent\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eUrine \/ serum \/ plasma\u003c\/td\u003e \u003ctd\u003e✓ Excellent\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eCell culture media\u003c\/td\u003e \u003ctd\u003e✓ Excellent\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eDilute acids (\u0026lt;10%)\u003c\/td\u003e \u003ctd\u003e✓ Good\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eDilute alkalies (pH \u0026lt;12)\u003c\/td\u003e \u003ctd\u003e✓ Good\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eShort-chain alcohols (brief)\u003c\/td\u003e \u003ctd\u003e✓ Good\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eDMSO (≤10%)\u003c\/td\u003e \u003ctd\u003e✓ Good — brief contact\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eAutoclave (121°C)\u003c\/td\u003e \u003ctd\u003e✗ Not compatible\u003c\/td\u003e \u003c\/tr\u003e \u003ctr\u003e \u003ctd\u003eStorage at -20°C\u003c\/td\u003e \u003ctd\u003e✓ Suitable — LDPE retains flexibility\u003c\/td\u003e \u003c\/tr\u003e \u003c\/tbody\u003e \u003c\/table\u003e \u003ch2\u003eLaboratory Applications\u003c\/h2\u003e \u003cp\u003eThe serves microbiology culture tube programs, clinical chemistry and hematology tube archiving, and any laboratory requiring friction-fit sealed closure on 16 mm OD test tubes.\u003c\/p\u003e \u003ch2\u003eU.S. Manufacturing, Quality \u0026amp; Institutional Procurement\u003c\/h2\u003e \u003cp\u003eEvery Caplugs® Evergreen lot is precision-molded at our California manufacturing facility and subject to rigorous dimensional inspection and material purity verification. We supply reference laboratories, hospital systems, and federal procurement offices under institutional pricing programs with blanket-order support and same-day shipping. \u003ca href=\"#request-sample\"\u003eRequest a free sample below\u003c\/a\u003e to validate fit before committing to volume.\u003c\/p\u003e \u003ch2\u003eFrequently Asked Questions — Caplugs® Evergreen \u003c\/h2\u003e \u003ch3\u003eWhat tube formats use 16 mm OD and fit the stopper?\u003c\/h3\u003e \u003cp\u003eThe fits 16 mm outer diameter test tubes, including: 16 × 100 mm, 16 × 125 mm, and 16 × 150 mm glass and PS test tubes, large clinical chemistry and serology tubes. Always validate fit with a sample before bulk purchase — opening diameter varies within the 16 mm OD range by wall thickness.\u003c\/p\u003e \u003ch3\u003eIs there a colored stopper available for 16 mm tubes?\u003c\/h3\u003e \u003cp\u003eRed (300-2916-R20) is available for 16 mm tubes at the same $66.96\/1000 price. Choose Natural for universal use with any labeling system; choose Red when serum-specimen visual routing is a workflow requirement.\u003c\/p\u003e \u003ch3\u003eWhy is LDPE used for stopper caps rather than PP or PS?\u003c\/h3\u003e \u003cp\u003eStopper-style caps work by friction fit — the plug must compress under insertion and spring back against the tube inner wall. PP and PS are too rigid for this and crack under repeated insertion\/removal cycles. LDPE's low-density flex allows thousands of insertion cycles without fracture, retains flexibility at -20°C to prevent brittle failure, and provides chemical inertness to clinical specimen matrices.\u003c\/p\u003e \u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"Product\",\n  \"name\": \"Test Tube Stopper Caps, For 16 mm Test Tubes, Non-Sterile, Low-Density Polyethylene (LDPE), Natural \\u2014 300-2916-020 | 1000\/Bag | Caplugs\\u00ae Evergreen\",\n  \"description\": \"Caplugs\\u00ae Evergreen 300-2916-020. LDPE test tube stopper caps, 16 mm, natural, 1000\/Bag. Culture tubes, specimen archiving. BPA-free. USA.\",\n  \"sku\": \"3002916020E1\",\n  \"mpn\": \"300-2916-020\",\n  \"material\": \"Low-Density Polyethylene (LDPE)\",\n  \"color\": \"Natural\",\n  \"brand\": {\n    \"@type\": \"Brand\",\n    \"name\": \"Caplugs\\u00ae Evergreen\"\n  },\n  \"manufacturer\": {\n    \"@type\": \"Organization\",\n    \"name\": \"Caplugs\\u00ae Evergreen\",\n    \"address\": {\n      \"@type\": \"PostalAddress\",\n      \"addressCountry\": \"US\",\n      \"addressRegion\": \"CA\"\n    }\n  },\n  \"offers\": {\n    \"@type\": \"Offer\",\n    \"price\": \"66.96\",\n    \"priceCurrency\": \"USD\",\n    \"availability\": \"https:\/\/schema.org\/InStock\",\n    \"itemCondition\": \"https:\/\/schema.org\/NewCondition\",\n    \"seller\": {\n      \"@type\": \"Organization\",\n      \"name\": \"LabSupplies\"\n    }\n  },\n  \"additionalProperty\": [\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"Pack Size\",\n      \"value\": \"1000 \/ Bag\"\n    },\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"Sterility\",\n      \"value\": \"Non-Sterile\"\n    },\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"Country of Origin\",\n      \"value\": \"United States\"\n    },\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"BPA Free\",\n      \"value\": \"Yes\"\n    },\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"Tube OD\",\n      \"value\": \"16 mm\"\n    },\n    {\n      \"@type\": \"PropertyValue\",\n      \"name\": \"Cap Style\",\n      \"value\": \"Stopper (plug-in friction fit)\"\n    }\n  ]\n}\n\u003c\/script\u003e \u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What tube formats use 16 mm OD and fit the 300-2916-020 stopper?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"The 300-2916-020 fits 16 mm outer diameter test tubes, including: 16 \\u00d7 100 mm, 16 \\u00d7 125 mm, and 16 \\u00d7 150 mm glass and PS test tubes, large clinical chemistry and serology tubes. Always validate fit with a sample before bulk purchase \\u2014 opening diameter varies within the 16 mm OD range by wall thickness.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is there a colored stopper available for 16 mm tubes?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Red (300-2916-R20) is available for 16 mm tubes at the same $66.96\/1000 price. Choose Natural for universal use with any labeling system; choose Red when serum-specimen visual routing is a workflow requirement.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Why is LDPE used for stopper caps rather than PP or PS?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Stopper-style caps work by friction fit \\u2014 the plug must compress under insertion and spring back against the tube inner wall. PP and PS are too rigid for this and crack under repeated insertion\/removal cycles. LDPE's low-density flex allows thousands of insertion cycles without fracture, retains flexibility at -20\\u00b0C to prevent brittle failure, and provides chemical inertness to clinical specimen matrices.\"\n      }\n    }\n  ]\n}\n\u003c\/script\u003e","brand":"Caplugs® Evergreen","offers":[{"title":"Default Title","offer_id":48567633314024,"sku":"300-2916-020","price":66.96,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0694\/5361\/1240\/files\/300-2916-020_01.jpg?v=1779052380","url":"https:\/\/labsupplies.com\/products\/caplugs-300-2916-020-ldpe-test-tube-stopper-16mm-natural","provider":"LabSupplies.com","version":"1.0","type":"link"}