20mm Pharmaceutical Vial Seals & Caps

This hub lists every 20mm vial cap and seal Autofits manufactures: the FlipTop® Optima flip-off, the FlipTop® Pull-Ring, the all-aluminium tear-down, and the all-aluminium tear-off. The 20mm seal is the most widely specified injectable closure, crimped over a 20mm rubber stopper to ISO 8362-1. Use the matrix below to compare construction, dimensions, and opening method before you specify a part.

Key takeaways

Autofits offers the 20mm size in four constructions: FlipTop® Optima flip-off, FlipTop® Pull-Ring, all-aluminium tear-down, and all-aluminium tear-off.
All four crimp over a standard 20mm vial neck and stopper to ISO 8362-1; they differ in how the seal opens and whether it carries a plastic top.
The 20mm Optima inner aluminium diameter is 20.22 mm (min) with a total seal height of 9.02 to 9.91 mm.
Maximum opening force for the 20mm range is 35 N.
Standard packing is 6,000 seals per box (2,000 x 2 bags), with Tyvek bagging and RTU or RTS delivery available.
For the full size index see products by size; for all constructions see the products page.

Which Autofits products come in 20mm

The 20mm neck is the most complete in the Autofits line, supported across all four constructions:

FlipTop® Optima (aluminium-plastic flip-off): a moulded plastic button you flip up to expose a small injection point while the aluminium skirt stays crimped. Bridge, Button, and Flower designs; glossy, matte, embossed, or printed finishes. See FlipTop® Optima 20mm.
FlipTop® Pull-Ring (aluminium-plastic): the whole seal detaches once the PP disc is detached; you pull the aluminium ring and open anticlockwise. Often marked for oral use. See pull-ring seals.
Tear-down (all-aluminium): a one-piece aluminium seal with a perforated section torn down to access the stopper, no plastic top. See tear-down seals.
Tear-off (all-aluminium): a one-piece aluminium seal opened by tearing the metal top away to expose the stopper. See tear-off seals.

20mm product matrix

All dimensions in millimetres, transcribed from the Autofits engineering drawings.

Product	Construction	Inner Ø (D1)	Total height	Alu thickness	How it opens	Product page
FlipTop® Optima	Aluminium-plastic flip-off	20.22 (min)	9.02–9.91	0.16–0.20	Flip plastic button up (6 taper bridges)	Optima 20mm
FlipTop® Pull-Ring	Aluminium-plastic	20.00–20.60	9.00–10.00	0.18–0.22	Pull alu ring, open anticlockwise, full seal off	Pull-ring seals
Tear-down	All-aluminium	20.50–20.70	7.50–8.50	0.18–0.22	Tear down perforated section (2 taper bridges)	Tear-down seals
Tear-off	All-aluminium	20.00–20.60	7.40–8.00	0.16–0.20	Tear aluminium top away (2 bridges)	Tear-off seals

The 20mm tear-off has a perforation diameter of 9.70 to 10.50 mm, and the 20mm tear-down has a perforation diameter of 12.90 to 13.20 mm.

Vial neck and ISO 8362-1 sizing for 20mm

A 20mm seal is specified to the vial neck finish, not to the vial volume. The crown bore, flange diameter, and flange thickness of the glass neck are defined in ISO 8362-1, and a 20mm seal is dimensioned to crimp cleanly over a matched 20mm stopper seated in that neck. The 20mm finish is the most common injectable finish and spans a wide range of fill volumes. Always confirm that the seal, the rubber stopper, and the glass vial share the same nominal 20mm neck finish so the crimp seats square and the rolled skirt forms a consistent residual seal force.

Opening force and standard packing for 20mm

From the FlipTop Seals dossier, the 20mm size has a maximum opening force of 35 N. Opening force varies with the number and taper of the bridges, and the 20mm Optima uses 6 taper bridges.

Standard packing is 6,000 seals per box (2,000 x 2 bags) in a 420 x 270 x 320 mm box. Tyvek bagging is available, and seals can be delivered Regular, Ready-to-Use (RTU, gamma or ETO sterilized), or Ready-to-Sterilize (RTS), double-bagged for aseptic areas. Minimum order quantity, colour selection, and lead times are confirmed on enquiry.

Quality and standards

20mm seals are produced under the Autofits quality system: ISO 9001:2015, ISO 14001:2015, and ISO 15378:2017 (GMP), supported by a Drug Master File (DMF 18100) and CFDA registration. The aluminium-plastic constructions follow ISO 15378:2017 and ISO 8362-6; the all-aluminium tear-off and tear-down relate to ISO 8362-3. PP discs are moulded in-house on Japanese Toyo injection machines, washing is fully automated, and every seal passes 100% high-speed camera inspection. Assembly takes place in an ISO Class 8 cleanroom inside the 75,000 sq ft Nashik facility. AQL is critical nil, major NMT 2.5%, minor NMT 4%, and is tailorable. Full certification detail is on the quality page.

Frequently asked questions

What is a 20mm vial cap used for?

A 20mm vial cap is the most widely specified injectable closure. It crimps over a 20mm rubber stopper seated in a 20mm vial neck finish to ISO 8362-1, compressing the stopper against the glass to form the sterile seal. Autofits supplies the 20mm size as a flip-off, a pull-ring, a tear-down, or a tear-off.

What is the difference between the 20mm constructions?

The FlipTop® Optima flip-off has a plastic button you flip up to expose a small injection point while the aluminium stays crimped. The FlipTop® Pull-Ring lets the whole seal detach once the PP disc is removed. The all-aluminium tear-down has a perforated section torn down to reach the stopper. The all-aluminium tear-off has the metal top torn away entirely. All four seal the vial through the crimp; they differ in how you open them.

What is the opening force of a 20mm seal?

The maximum opening force for the 20mm range is 35 N. Actual force varies with the bridge count and taper of the specific design.

How are 20mm seals packed and delivered?

Standard packing is 6,000 seals per box (2,000 x 2 bags) in a 420 x 270 x 320 mm box. Tyvek bagging is available. Seals can be supplied Regular, Ready-to-Use (gamma or ETO sterilized), or Ready-to-Sterilize, double-bagged for aseptic filling areas.

Which 20mm seal should I choose?

For routine injectables and colour-coded identification, the FlipTop® Optima flip-off is the usual choice. Where the whole seal needs to come off, the Pull-Ring or the all-aluminium tear-down and tear-off suit better. Selection also depends on whether you need an aluminium-plastic or an all-aluminium closure and on your sterilization route. Share the application and we can advise.

Are 20mm seals available in different colours?

Yes. The seals are available in a wide range of colours, matte or glossy, customised to requirement, and the aluminium can be printed or embossed. Specific colours and any printing are confirmed at the quotation stage.

Sources

Autofits engineering drawings and FlipTop Seals product dossier (on file).
ISO: ISO 8362-1, Injection containers and accessories, Part 1: Injection vials made of glass tubing (https://www.iso.org/standard/63461.html)
ISO: ISO 15378:2017, Primary packaging materials for medicinal products, GMP requirements (https://www.iso.org/standard/70326.html)

*Last updated: 2026-06-26. This page is general technical information, not regulatory or compliance advice; confirm current dimensions, standard editions, and requirements with Autofits and the issuing bodies.*