#7 Drilled Rubber Stopper (DRS)
The #7 Drilled Rubber Stopper (DRS) is a pure white gum laboratory stopper. The top diameter is 1 7/16", the bottom diameter is 1 3/16", and it has a 3/8" hole drilled in the center, the perfect size for an airlock.
Frequently purchased with a fermentation lock.
Also available as a #7 solid rubber stopper.