Dissolved oxygen bottles, Winkler pattern

Winkler pattern. Soda-lime glass.
For determination of dissolved oxygen in water. The measured capacity is specified to &plusminus; 0,01ml. With white labelling area. Solid, bevelled glass stopper, secured with an accessory spring clip. Each bottle is adjusted to the relevant stopper. Stoppers and bottles are therefore not interchangeable. Each bottle and its stopper is marked with a unique, matching identification number.
Nominal capacity 250 to 300 ml
NS 19/26
Snap-on clip 9.304 051