{"product_id":"caplugs-300-2909-020-ldpe-test-tube-stopper-9mm-natural","title":"Test Tube Stoppers, HDPE, Natural — 300-2909-020 | 1000\/Bag | Caplugs® Evergreen","description":"\u003ch2\u003eTest Tube Stoppers for 9 mm OD Tubes — LDPE, Natural, 1000\/Bag (300-2909-020)\u003c\/h2\u003e\n\u003cp\u003eThese natural Low-Density Polyethylene (LDPE) stopper caps are designed to close standard small test tubes and culture tubes with a 9 mm outer diameter using a plug-in friction fit that seats against the inner tube wall without threading or snap-over engagement. Supplied non-sterile in a convenient 1000\/Bag pack, part number 300-2909-020 is well suited to high-volume tube capping programs in clinical labs, microbiology, and research settings. LDPE's inherent flexibility allows the stopper plug to compress on insertion and recover to maintain a positive friction-fit seal through refrigerated storage, frozen archiving down to -20°C, and incubation up to +60°C without hardening or losing retention.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number (MPN)\u003c\/td\u003e\n\u003ctd\u003e300-2909-020\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube OD\u003c\/td\u003e\n\u003ctd\u003e9 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCap Style\u003c\/td\u003e\n\u003ctd\u003eStopper — plug-in friction fit\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eLow-Density Polyethylene (LDPE)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eColor\u003c\/td\u003e\n\u003ctd\u003eNatural\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTemperature Range\u003c\/td\u003e\n\u003ctd\u003e-20°C to +60°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSterility\u003c\/td\u003e\n\u003ctd\u003eNon-Sterile\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePack Size\u003c\/td\u003e\n\u003ctd\u003e1000\/Bag\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBPA \/ Phthalates\u003c\/td\u003e\n\u003ctd\u003eBPA-free; no phthalate plasticizers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCountry of Origin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eApplications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMicrobiology culture tube capping — seals TSB, BHI, and other broth media tubes during incubation to prevent contamination\u003c\/li\u003e\n\u003cli\u003eSpecimen archiving — retains closure on serum, plasma, and urine tubes during refrigerated and frozen storage through multiple freeze-thaw cycles\u003c\/li\u003e\n\u003cli\u003eClinical chemistry pre-analytical hold — friction-fit seal prevents evaporation from sample tubes awaiting analysis\u003c\/li\u003e\n\u003cli\u003eResearch reagent and buffer storage — closes stock solution and working reagent tubes in 9 mm OD format\u003c\/li\u003e\n\u003cli\u003ePneumatic tube transport — stopper retention prevents spillage and cross-contamination during in-facility specimen transport\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eChemical Resistance\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eReagent \/ Condition\u003c\/th\u003e\n\u003cth\u003eCompatibility\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eAqueous buffers \/ saline\u003c\/td\u003e\n\u003ctd\u003eExcellent\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUrine, serum, plasma matrices\u003c\/td\u003e\n\u003ctd\u003eExcellent\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBroth and culture media\u003c\/td\u003e\n\u003ctd\u003eExcellent\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDilute acids and bases\u003c\/td\u003e\n\u003ctd\u003eGood\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAlcohols (ethanol, isopropanol)\u003c\/td\u003e\n\u003ctd\u003eGood — short-term contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAcetone \/ aromatic solvents\u003c\/td\u003e\n\u003ctd\u003eNot recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChlorinated solvents\u003c\/td\u003e\n\u003ctd\u003eNot recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eQuality \u0026amp; Procurement\u003c\/h2\u003e\n\u003cp\u003eMade in USA, these Caplugs® Evergreen stopper caps are manufactured from BPA-free, phthalate-free LDPE resin engineered to maintain friction-fit flexibility across the full -20°C to +60°C working range. LDPE's low flex modulus makes it the material of choice for stopper-style closures — rigid materials such as PP, PS, or HDPE lack the compliance needed to compress on insertion and recover to seat reliably against the inner tube wall. LabSupplies.com is an authorized Caplugs® Evergreen dealer, shipping from USA inventory with tiered volume pricing available for institutional, clinical, and grant-funded procurement programs.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eWhy must these stoppers be LDPE rather than polypropylene or polystyrene?\u003c\/strong\u003e\u003cbr\u003eStopper-style caps rely on plug compression and elastic recovery to maintain a friction fit inside the tube. Polypropylene and polystyrene are significantly more rigid than LDPE and will crack or fail to seat rather than compress and recover — making LDPE the correct material choice for this closure format.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWill these stoppers stay in place during frozen storage and freeze-thaw cycling?\u003c\/strong\u003e\u003cbr\u003eYes. LDPE retains its flexibility down to -20°C, so the stopper maintains friction-fit engagement with the tube inner wall through repeated freeze-thaw cycles without hardening or losing retention.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eAre these tube stoppers sterile?\u003c\/strong\u003e\u003cbr\u003eNo — they are supplied non-sterile in 1000\/Bag packaging. For applications requiring sterile closures, contact your LabSupplies.com representative to confirm availability of sterile-packaged options within the Caplugs® Evergreen stopper range.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat other sizes are available in the Caplugs® Evergreen stopper range?\u003c\/strong\u003e\u003cbr\u003eThe Evergreen stopper line includes natural LDPE stoppers for 8 mm OD tubes (300-2908-020) and 10 mm OD tubes (300-2910-020), as well as a green 9 mm option (300-2909-G20) for color-coded tube identification workflows.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\":\"https:\/\/schema.org\/\",\"@type\":\"Product\",\"name\":\"Test Tube Stoppers, LDPE, Natural, 9 mm OD, 1000\/Bag — Caplugs® Evergreen 300-2909-020\",\"sku\":\"300-2909-020\",\"mpn\":\"300-2909-020\",\"brand\":{\"@type\":\"Brand\",\"name\":\"Caplugs® Evergreen\"},\"material\":\"Low-Density Polyethylene (LDPE)\",\"color\":\"Natural\",\"offers\":{\"@type\":\"Offer\",\"priceCurrency\":\"USD\",\"price\":\"46.60\",\"availability\":\"https:\/\/schema.org\/InStock\"}}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\":\"https:\/\/schema.org\/\",\"@type\":\"FAQPage\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Why must these stoppers be LDPE rather than polypropylene or polystyrene?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Stopper-style caps rely on plug compression and elastic recovery to maintain a friction fit inside the tube. Polypropylene and polystyrene are significantly more rigid than LDPE and will crack or fail to seat rather than compress and recover — making LDPE the correct material choice for this closure format.\"}},{\"@type\":\"Question\",\"name\":\"Will these stoppers stay in place during frozen storage and freeze-thaw cycling?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. LDPE retains its flexibility down to -20°C, so the stopper maintains friction-fit engagement with the tube inner wall through repeated freeze-thaw cycles without hardening or losing retention.\"}},{\"@type\":\"Question\",\"name\":\"Are these tube stoppers sterile?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No — they are supplied non-sterile in 1000\/Bag packaging. For applications requiring sterile closures, contact your LabSupplies.com representative to confirm availability of sterile-packaged options within the Caplugs® Evergreen stopper range.\"}},{\"@type\":\"Question\",\"name\":\"What other sizes are available in the Caplugs® Evergreen stopper range?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The Evergreen stopper line includes natural LDPE stoppers for 8 mm OD tubes (300-2908-020) and 10 mm OD tubes (300-2910-020), as well as a green 9 mm option (300-2909-G20) for color-coded tube identification workflows.\"}}]}\u003c\/script\u003e","brand":"Caplugs® Evergreen","offers":[{"title":"Default Title","offer_id":48567084548328,"sku":"300-2909-020","price":46.6,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0694\/5361\/1240\/files\/300-2909-020_01.jpg?v=1779031397","url":"https:\/\/labsupplies.com\/products\/caplugs-300-2909-020-ldpe-test-tube-stopper-9mm-natural","provider":"LabSupplies.com","version":"1.0","type":"link"}