Stopcock plug pullers are used to remove the PTFE plug from the threaded barrel in old style (see 89062-406 series) threaded stopcocks.

Plug pullers are not compatible with hooded style stopcocks (as supplied in 89062-594 series). The flat nylon disc has a matching thread in the center, a slit on one side, and a spring steel wire in a groove on the outside edge. Simply spread the disc over the thread on the plug, effectively increasing the thread length, and turn the plug until the O-rings release.