The rubber stopper provides the hermetic seal. When a bromobutyl rubber stopper is inserted into a vial neck and the aluminium cap is crimped over it, the crimping process applies a controlled downward and inward force that seats the stopper fully into the neck and compresses the stopper plug against the glass neck inner wall - creating the gas-tight, liquid-tight seal that maintains container closure integrity (CCI) throughout the product's shelf life. The stopper's elastomeric properties (compression set, hardness, elastomeric recovery) determine the quality of this seal.

The aluminium cap holds the stopper in the seated position permanently. Without the crimp cap, the stopper's compressive seal force against the neck would gradually relax through the stopper's natural compression set - and the stopper could be displaced by headspace pressure during autoclaving, lyophilisation, or distribution. The aluminium skirt, once crimped under the neck flange, locks the stopper's seating depth and prevents any axial movement - maintaining the seal geometry for the entire shelf life.

The two components must be dimensionally matched to the same nominal size - a 13mm stopper and a 13mm cap, or a 20mm stopper and a 20mm cap. Within each nominal size, the specific outer diameter of the stopper's plug section and the inner diameter of the aluminium cap's skirt must be compatible - the cap must fit over the stoppered neck without requiring excessive crimping force and must crimp consistently to the specified crimp depth and width. Sourcing cap and stopper from different suppliers with different dimensional tolerances introduces a risk of CCI failure or inconsistent crimping that must be resolved by additional validation testing.

When sourced as a matched pair from a single supplier - where the stopper and cap dimensions are confirmed compatible - the dimensional risk is eliminated and the qualification path is simplified. We supply both the aluminium flip off cap and the matched bromobutyl rubber stopper in 13mm and 20mm sizes from our own manufacturing facilities, with a confirmed dimensional compatibility statement available on request.

For 2ml · 3ml · 5ml small injection vials

The 13mm closure system - 13mm aluminium flip off cap matched with a 13mm bromobutyl rubber stopper - closes the small-format pharmaceutical injection vial range. The 13mm neck finish is standard on 2ml, 3ml, and 5ml tubular glass vials, the most common container for single-dose injectable products including peptides, hormones, allergens, and high-potency small-volume injectables.

✓ 13mm Al flip off cap - blue, red, green or any standard colour

✓ 13mm bromobutyl stopper - serum or two-leg lyo profile

✓ For 2ml, 3ml, 5ml vials with 13mm ISO 8362-2 neck

✓ PTFE-coated stopper option for sensitive formulations

✓ Crimped with standard 13mm die

For 5ml · 10ml · 20ml · 50ml standard injection vials

The 20mm closure system is the pharmaceutical industry's most widely used injectable vial closure - the 20mm aluminium flip off cap matched with a 20mm bromobutyl rubber stopper closes the full standard pharmaceutical injection vial range from 5ml to 50ml. The 20mm neck finish is specified on the broadest range of injectable products: antibiotics, biologics, vaccines, hormones, lyophilised proteins, and multi-dose preparations. This is the standard system that should be specified unless the 13mm small-vial format is specifically required.

✓ 20mm Al flip off cap - full 12-colour range

✓ 20mm bromobutyl stopper - serum or two-leg lyo profile

✓ For 5ml–50ml vials with 20mm ISO 8362-2 neck

✓ PTFE-coated stopper for biologics and sensitive APIs

✓ Crimped with standard 20mm die ★

Serum or lyo profile · most injectable formulations

The standard uncoated bromobutyl rubber stopper is appropriate for the vast majority of pharmaceutical injectable formulations - aqueous solutions of antibiotics, electrolytes, analgesics, small-molecule drugs, multi-dose vaccines, and hormone preparations. Good chemical resistance, reliable self-sealing, well-characterised extractables profile, and the lowest cost of the three grades. The correct starting specification for stopper selection - upgrade to Grade 2 or Grade 3 only when formulation-specific data indicates a need.

✓ For most aqueous pharmaceutical injectable formulations

✓ Well-characterised extractables - USP <381> / EP 3.2.9

✓ Most economical stopper grade

✓ Available in serum and two-leg lyo profiles

Low extractables · biologics · peptides · sensitive APIs

The PTFE or fluoropolymer-coated bromobutyl stopper has a fluoropolymer barrier coating on all formulation-contact surfaces - reducing extractables migration from the rubber compound into the pharmaceutical formulation, reducing coring and sub-visible particle generation on needle penetration, and improving needle penetration force consistency. Specified for biologics (mAb, proteins, ADC), peptide injectables, and any formulation where the E&L programme has identified rubber-derived extractables as a risk requiring mitigation. The coating does not change the stopper's sealing, self-sealing, or crimping performance.

✓ PTFE coating reduces extractables migration ★

✓ Reduced coring and sub-visible particle generation

✓ Recommended for biologics, mAb, and sensitive peptides

✓ Full extractables TDS - BioPhorum-consistent data

Freeze-dry cycle · half-insert and full-seat positions

The two-leg (lyo) stopper is specified for vials that will undergo a lyophilisation (freeze-drying) cycle. The two-leg profile allows the stopper to sit in the half-inserted position during the lyo cycle - legs inside the vial neck, stopper head above the neck opening, creating a vapour path for water vapour to escape during primary drying - and to be fully seated by the lyophiliser shelf at cycle end, sealing the vial under vacuum. The same 13mm or 20mm aluminium flip off cap is then crimped over the fully-seated lyo stopper after the vials exit the lyophiliser. PTFE-coated two-leg lyo stoppers are available for lyophilised biologics.

✓ Two-leg profile for freeze-drying cycle compatibility

✓ Half-insert position stable during lyo cycle

✓ Al cap crimped after lyo - same cap as serum stopper ★

✓ PTFE-coated lyo stopper available for biologics

This is the foundational decision - the nominal neck finish size of your glass injection vial determines the cap and stopper size. Check your vial specification or measure the outer neck diameter. If in doubt, the 13mm neck is standard on 2ml–5ml vials; the 20mm neck is standard on 5ml–50ml vials.

13mm 20mm ★ Confirm from vial spec

Most pharmaceutical injectable products use the standard flip off cap. Solid top is specified for single-dose products requiring maximum tamper evidence or no flip-tab projection above the stopper surface. Six-stem is used in specific regional markets and small-vial formats. If unsure, specify flip off.

Flip off ★ Solid top Six-stem (13mm)

Select the PP flip tab colour for your product identification system. Check against your institution's or company's pharmaceutical colour-coding standard if one exists. If no colour standard applies, blue is the most neutral starting choice for a new product. 12 standard colours available; custom colours on request.

Blue Red · Green · Black Any of 12 standard Custom colour

If your product is filled as a liquid and sealed immediately - specify serum (standard) stopper. If your product will undergo a freeze-drying cycle - specify the two-leg lyophilisation stopper. Mixed product ranges may require both profiles in the same size.

Serum (standard) ★ Two-leg lyo

Start with standard uncoated bromobutyl for most formulations. Upgrade to PTFE-coated if your E&L programme indicates rubber-derived extractables are a concern, or if your formulation is a biologic, mAb, or sensitive peptide. Specify chlorobutyl (CIIR) only if an E&L data finding specifically supports it.

Standard BIIR ★ PTFE-coated BIIR Chlorobutyl CIIR Coated CIIR

We supply all three components of the closure system: the glass vial, the rubber stopper, and the aluminium cap. Tell us your vial volume (2ml, 3ml, 5ml, 10ml, 20ml, etc.) and whether you want the vial included in your sample kit alongside the cap and stopper. Complete vial + stopper + cap kits are dispatched within 48 hours of enquiry confirmation.

Cap + stopper only Complete vial + cap + stopper kit ★

Commercial filling · validated closure system

Commercial pharmaceutical manufacturers filling injectable drug products in glass vials who specify the cap and stopper as a matched pair from a single supplier to simplify qualification and supply chain management.

mAb · protein · biologic · lyo · PTFE-coated

Biologic drug manufacturers specifying PTFE-coated bromobutyl stoppers with matched 20mm flip off caps for sensitive protein injectables - requiring full extractables TDS documentation alongside the physical samples.

Multi-client · platform closure system · 13mm + 20mm

Contract fill-finish organisations maintaining both 13mm and 20mm closure systems as platform specifications - sourcing matched cap-and-stopper sets in all sizes and grades from a single supplier to simplify cross-product qualification.

Custom injectable · matched pair · small-batch

Sterile compounding pharmacies producing custom injectable preparations who need matched cap-and-stopper kits in small quantities with fast dispatch - without the minimum order quantities typical of large-volume pharmaceutical suppliers.

Phase I–III · regulatory submission · CCI validation

Clinical supply and CMC development teams requesting complete three-component kits (vial + stopper + cap) for container-closure compatibility studies, CCI validation, and primary packaging system descriptions in regulatory submissions.

Reference standards · stability · sample preparation

Research laboratories packaging reference standard solutions, pharmacokinetic study samples, and stability test preparations in pharmaceutical-grade vials with matched cap-and-stopper sets for analytical accuracy and sample integrity.