12 mm Test Tube Stoppers — LDPE, Red, BD® Vacutainer-Compatible | 1000/Bag (300-2912-R20)
These red LDPE plug-in stopper caps fit standard 12 mm OD test tubes — including 12 × 75 mm and 12 × 100 mm glass and polystyrene culture tubes as well as BD® Vacutainer-compatible collection tube formats — and are supplied non-sterile in 1000/Bag for high-volume laboratory capping programs. The red color mirrors the CLSI H3 red-top serum tube convention, making these stoppers an intuitive fit for clinical chemistry, immunoassay, and serology workflows that route specimens by tube color. Low-density polyethylene construction provides the flex modulus necessary for reliable friction-fit retention across repeated insertion and removal cycles without fracture.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-2912-R20 |
| Tube OD | 12 mm |
| Cap Style | Stopper — plug-in friction fit |
| Material | Low-Density Polyethylene (LDPE) |
| Color | Red |
| Color Convention | CLSI H3 red-top serum tube standard |
| Compatible Tube Formats | 12 × 75 mm and 12 × 100 mm glass and PS culture tubes; BD® Vacutainer-compatible sizes |
| 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 (California) |
Applications
- Clinical chemistry & serology specimen archiving: Red stoppers follow the CLSI H3 convention for serum tubes, making color-coded specimen routing straightforward across clinical chemistry, immunoassay, and serology benches.
- Microbiology culture tube capping: LDPE flexibility maintains a reliable seal on TSB, BHI, LB broth, and other culture media tubes throughout 37°C incubation cycles.
- Refrigerated and frozen storage: Flexibility is retained at -20°C, enabling clean insertion and removal during frozen archive access without stopper fracture.
- Cell culture and virus propagation: Stopper-style closure on 12 mm suspension culture tubes prevents contamination while permitting controlled gas exchange.
- Pneumatic tube transport: LDPE friction retention withstands the acceleration forces of clinical pneumatic transport systems, keeping sample tubes securely closed in transit.
- Pre-analysis sample tube closure: Suitable for sealing serum, plasma, and urine tubes prior to and during analyzer loading in clinical laboratory workflows.
Compatibility
The 300-2912-R20 stopper is designed to fit the 12 mm OD tube diameter used by BD® Vacutainer® collection tubes and the standard 12 × 75 mm and 12 × 100 mm glass and polystyrene culture tube formats common across clinical and research laboratories. The 12 mm diameter represents the broadest compatibility range in the Caplugs® Evergreen stopper series, covering the tube sizes most frequently used in clinical chemistry, microbiology, and hematology specimen programs. Laboratories currently using OEM red stoppers with BD® or equivalent 12 mm tube systems can transition to these stoppers as a direct plug-in replacement; verify the OD of your specific tube lot before committing to large-volume orders.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers, saline, water | Excellent |
| Serum, plasma, urine, whole blood | Excellent |
| Microbiology broth media (TSB, BHI, LB) | Excellent |
| Dilute acids and bases | Good |
| Ethanol and alcohols | Good — short-term contact |
| Acetone / chlorinated solvents | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
Quality & Procurement
Made in USA (California), these Caplugs® Evergreen stoppers are produced from BPA-free, phthalate-free LDPE resin under ISO 9001 quality management, ensuring consistent dimensional tolerances and material purity across every bag. LabSupplies.com is an authorized Caplugs® Evergreen dealer shipping from USA inventory, with same-business-day dispatch available for stocking items and volume pricing tiers available for institutional, hospital, and grant-funded procurement programs.
Frequently Asked Questions
Are these stoppers sterile?
No — they are supplied non-sterile in 1000/Bag packaging. For sterile applications such as aseptic cell culture or virus propagation, surface-sterilize stoppers before use according to your facility's SOP.
Will these stoppers fit BD® Vacutainer® tubes?
Yes — BD® Vacutainer® collection tubes use a 12 mm OD format, and these stoppers are designed to fit standard 12 mm OD tubes. Verify the OD of your specific tube lot before large-volume deployment, as minor dimensional variation can exist between manufacturers.
Can these stoppers be used at freezer temperatures for archived samples?
Yes — LDPE retains its flexibility at -20°C, so the stoppers can be inserted and removed from frozen archive tubes without becoming brittle or cracking. The rated temperature range is -20°C to +60°C.
Why red? Does the color indicate anything specific?
Red follows the CLSI H3 convention for serum collection tubes, the most widely recognized clinical tube color designation. Using red stoppers on 12 mm serum specimen tubes allows laboratory staff to route and identify specimens by color without additional labeling, reducing handling errors in high-throughput clinical workflows.