These are replacement glass No. 4 Standard Taper stopcock plugs with 4mm diameter bores for No. 7280 PYREX® straight bore glass stopcocks.
Since several different bored sizes may be drilled through any given size of plug, the approved method of designating the size of a standard taper stopcock is by bore diameter only. Interchangeable ground glass stopcocks are not intended for high vacuum apparatus or for use with light liquids. When, by constant abrasion, a stopcock has become so worn that the shell is enlarged, or the plug is diminished in size, it is recommended that you replace the plug.
These are replacement glass Standard Taper stopcock plugs with various diameter bores for Cat. No. 7280 PYREX® straight bore glass stopcocks.