Description
Octagonal cap stopper NS 12/21 is a solid ground-joint stopper produced from SBW glass in accordance with DIN 12252. Sized for standard taper joints NS 12/21, it delivers a tight, chemically inert seal for laboratory flasks, bottles and reaction vessels. The solid glass construction preserves joint geometry and supports a dependable glass-to-glass closure under typical laboratory conditions. Its octagonal cap head offers a secure grip for hand tightening and easy removal, reducing the risk of slippage during frequent opening and closing cycles. Offered as one piece with a net weight of 0,012 kg, the stopper is well suited to everyday analytical and preparative workflows that require inert contact surfaces. The article from manufacturer Witeg fits established NS joint assemblies and can be used to close reagents, intermediates or samples during storage, mild heating or reaction steps. An uncoated glass finish permits clear visual checks and simple cleaning, making this stopper a practical accessory for research, quality-control and teaching environments that standardise on ground-joint glassware.
This article is part of Screw caps & closures, in Stoppers, caps & closures.
Key features
- Pack size: 1 pc
- Joint size: NS 12/21
- Material: SBW glass
- Design: Solid octagonal cap
- Standard: DIN 12252
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Questions about ST-stopper ST 12/21 octonal
What is this article?
ST-stopper ST 12/21 octonal is the article on this page. Luminix Health distributes Witeg for laboratory use. It sits in Screw caps & closures, inside Stoppers, caps & closures, in Labware.
A screw cap has a thread and a liner. The thread has to match the bottle. The liner has to survive the liquid: a pulp liner fails in a solvent that a PTFE-faced liner ignores. The colour of the cap is not the specification.
A closure is the part that decides whether a bottle stays shut and whether the contents attack the seal. A ground-glass stopper matches a ground neck. A screw cap needs the right thread and a liner that survives the liquid. Rubber and silicone stoppers push into a mouth. The liner, not the colour of the cap, is the chemical choice. The vessels they close are indexed under ISO laboratory glassware.
Which category should I open next?
The category is Stoppers, caps & closures. The sub-category is Screw caps & closures. The catalogue is Labware.
Shelves beside this one are Rubber & silicone stoppers, Ground-joint glass stoppers, Lids & seals and Closures (other).
What should I check before I order?
When this page shows a safety data sheet, use that manufacturer file. Hazard text does not belong in the sales description. For a pack size, a grade or a certificate that is not on the page, send a quote request or contact the team.
How does ordering and shipping work?
Luminix Health distributes this article from the heart of Europe. Articles in stock ship within 2–5 business days. Standard delivery is free from €250 excl. VAT. Cold-chain goods and dangerous goods under ADR are never included in that free delivery. The terms are in the Shipping Policy. The full brand index is on shop by brand. Who we are is on about us.
Which other categories should I open?
The seven catalogues are Labware, Lab chemicals, Lab instruments, Lab consumables, Chromatography equipment, Lab safety equipment and Life Science & Microbiology.