Test Tube Stoppers, HDPE, Natural — 300-2910-020 | 1000/Bag | Caplugs® Evergreen

Test Tube Stoppers for 10 mm OD Tubes — LDPE, Natural, 1000/Bag (300-2910-020)

These natural Low-Density Polyethylene (LDPE) stopper caps provide a secure plug-in friction-fit closure for standard 10 mm OD test tubes and culture tubes — the most common tube diameter in general laboratory and clinical formats. Part number 300-2910-020 is supplied non-sterile in 1000/Bag for high-volume capping programs, with a rated temperature range of −20°C to +60°C that keeps the stopper pliable and retained through freeze-thaw cycles without cracking or losing grip. The plug inserts into the tube opening and seats against the inner tube wall by friction, providing a positive closure that prevents evaporation, contamination, and spillage without threading or snap-over engagement.

Technical Specifications

Applications

• Microbiology culture tube capping — seals TSB, BHI broth, and similar culture media tubes during incubation to prevent contamination while allowing easy re-access
• Specimen tube archiving — closes serum, plasma, and urine tubes during refrigerated or frozen storage at temperatures as low as −20°C
• Pneumatic tube transport — friction-fit retention prevents dislodgement and spillage during sample transit within hospital pneumatic systems
• General bench capping — non-sterile bulk packaging suits high-throughput workflows where tubes are capped, uncapped, and re-capped repeatedly throughout the day

Chemical Resistance

Quality & Procurement

Made in USA, these Caplugs® Evergreen stoppers are manufactured from BPA-free, phthalate-free LDPE resin under ISO 9001 quality management. LDPE is specifically required for the stopper format because its low flex modulus allows the plug to compress on insertion and recover against the tube's inner wall — the elastic retention behavior that rigid materials such as PP, PS, or HDPE cannot reliably provide. LabSupplies.com is an authorized Caplugs® Evergreen dealer shipping from USA inventory, with tiered volume pricing available for institutional, clinical, and high-throughput laboratory programs.

Frequently Asked Questions

Why must stopper caps be LDPE rather than polypropylene or polystyrene?
The stopper-plug format depends on the cap compressing slightly under insertion force and then recovering to grip the inner tube wall by friction. LDPE's low-density flex modulus provides exactly this behavior down to −20°C. Rigid materials like PP, PS, and HDPE lack sufficient elasticity in a plug geometry — they either fail to seat securely or fracture under repeated insertion, making LDPE the standard material choice for stopper-style closures.

What tube dimensions do these stoppers fit?
These stoppers are sized for tubes with a 10 mm outer diameter, including standard 10 × 75 mm culture tubes and similarly dimensioned clinical specimen tubes. If your tubes have a different OD — such as 8 mm or 9 mm — Caplugs® Evergreen offers corresponding stopper sizes in the same natural LDPE construction.

Are these stoppers sterile?
No — they are supplied non-sterile in 1000/Bag packaging. For most culture tube capping, archiving, and transport workflows, non-sterile bulk stoppers are standard practice; if your protocol requires sterile closures, consult your SOPs or contact our team for guidance on available options.

Can these be used for frozen specimen archiving at −20°C?
Yes. The LDPE material is rated down to −20°C and retains its flexibility at that temperature, so the friction-fit engagement is maintained through freeze-thaw cycles without the stopper hardening, cracking, or pulling free from the tube.