It's just masking tape to keep from marking / marring the leather, I work in a huge collision center, yellow masking tape everywhere.
I use it for both forming a pocket and for loosening up the heel, heel binding, and palm, and for forming break points. I like that it's a heavy 5 lb. dumbbell, I don't have to hit it too hard for it to still work but if I need to really beat a glove hard, it really works!
