12 mm Test Tube Stoppers — LDPE, Green, BD® Compatible | 300-2912-G20 | 1000/Bag
These green low-density polyethylene (LDPE) plug-in stopper caps are engineered for 12 mm OD test tubes, including standard 12 × 75 mm formats widely used across clinical chemistry, hematology, microbiology, and research workflows. Part number 300-2912-G20 ships 1000 stoppers per bag and provides a reliable friction-fit closure that stays engaged from –20°C frozen archive through 60°C incubation — making them equally suited for freeze-thaw cycling and bench incubation without hardening or losing retention.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-2912-G20 |
| Cap Style | Stopper — plug-in friction fit |
| Tube OD | 12 mm |
| Compatible Tube Format | Standard 12 × 75 mm test tubes |
| Material | Low-Density Polyethylene (LDPE) |
| Color | Green |
| Temperature Range | –20°C to +60°C |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag |
| BPA / Phthalates | BPA-free; no phthalate plasticizers |
| Country of Origin | USA |
Applications
- Microbiology culture tube capping: Seals TSB, BHI, LB broth, and other culture tubes during 37°C incubation; LDPE flexibility is fully retained at incubation temperatures.
- Specimen archiving: Prevents evaporation from serum, plasma, and urine tubes during extended refrigerated or frozen storage.
- Clinical chemistry sample sealing: LDPE is inert to serum and plasma matrices, making these stoppers appropriate for pre-analysis capping without risk of leaching into specimen contents.
- Cell culture and virus propagation tubes: Provides a secure yet removable closure for suspension cell culture and virus propagation workflows.
- Pneumatic tube transport: LDPE flex retention keeps the stopper seated through the acceleration forces encountered in clinical tube-transport systems.
- Color-coded batch and specimen routing: Green differentiates stoppered tubes visually in loading racks, supporting specimen-type designation or batch-identity workflows without secondary labels.
- Reagent and buffer tube storage: Caps buffer stocks, reagent aliquots, and other aqueous solutions for bench or cold-room storage.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers / saline | Excellent |
| Urine, serum, plasma | Excellent |
| Broth media (TSB, BHI, LB) | Excellent |
| Dilute acids and bases | Good |
| Alcohols (short-term contact) | Good |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
Quality & Procurement
Made in USA, these Caplugs® Evergreen stoppers are produced from BPA-free, phthalate-free LDPE resin under ISO 9001 quality management practices, ensuring consistent dimensional tolerances and friction-fit retention across every bag. LabSupplies.com is an authorized Caplugs® Evergreen dealer shipping from USA inventory, with same-business-day fulfillment typically available for stocking items and tiered volume pricing for high-throughput clinical programs, hospitals, and research institutions.
Frequently Asked Questions
Are these stoppers sterile?
No — the 300-2912-G20 is supplied non-sterile in 1000/Bag bulk packaging, which is appropriate for most clinical chemistry, specimen archiving, and general research applications. If sterile closure is required for your workflow, please contact us to confirm available options.
Will these stoppers fit tubes other than 12 × 75 mm?
These stoppers are designed for 12 mm OD test tubes, of which the standard 12 × 75 mm format is the most common. Compatibility with other tube lengths sharing the same 12 mm outer diameter is likely but should be verified against your specific tube wall thickness and inner diameter before committing to high-volume use.
Why choose green stoppers specifically?
Green is used in many laboratories as a color-code designation for a particular specimen type, priority level, or processing batch. Using a distinctively colored stopper like these allows staff to differentiate tube groups visually in racks and during processing, reducing sorting errors without requiring additional labels.
Can these stoppers be reused, and how do they perform through freeze-thaw cycles?
LDPE's low-density flex modulus allows the plug to compress on insertion and recover against the tube wall across repeated insertion and removal cycles. The material retains this flexibility from –20°C frozen storage through 60°C incubation, so friction-fit engagement is maintained through freeze-thaw cycling without the hardening or cracking associated with more rigid cap materials.