Quick Answer: The Red Rubber Stoppers Solid 21mm are size 21 solid bungs of red rubber, measuring 21 mm at the bottom, 24.5 mm at the top and 28 mm in length.
Last updated: October 2026
Key Features
Size 21 solid stopper in red rubber
Top 24.5 mm, bottom 21 mm, length 28 mm
Shore hardness in the range 46-55
Bottom diameter is moulded on the top face
Technical Specifications
Specification
Value
Size
21
Top diameter
24.5 mm
Bottom diameter
21 mm
Length
28 mm
Shore hardness
46-55
Bung type
Solid, rubber
About This Product
A size 21 stopper for sealing glassware: it is suited to 125 ml conical flasks and to flasks of 50-100 ml. The bung is solid red rubber with a Shore hardness between 46 and 55, and the bottom diameter appears moulded on its top face. Export supply of the Red Rubber Stoppers Solid 21mm can be arranged to laboratories and schools in Iran, Tunisia, Namibia, Indonesia, Nicaragua and Malta.
Frequently Asked Questions
Q1. Which flasks does a size 21 stopper suit? It is suited to 125 ml conical flasks and to flasks of 50-100 ml.
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