Tension Lock TTL10 (US. PAT.NO.10366680)

KEEP DRUM HEAD TENSION WHILE PLAYING
The Tension Lock is an accessory to prevent tension bolts from loosening while playing. Simply set it on the tension bolt head – its unique shape fits perfectly. On the other hand, you can tune the drum without having to detach the Tension Lock, thanks to an elastic O-ring around its hole. It is a small accessory, but filled with TAMA's unique ideas.