Finally, a way to put all those pesky tribbles to work! With every step, your Tribble Slippers will purr happily (You will need to flip the switch to "on" to hear the sounds). Requires 3 LR44 batteries for each slipper (included). 100% polyester, One Size Fits Most. (The footbed is 11" long. Approx. Men's size 11/Women's 12) Washing Instructions: Surface wash only. Remove battery box before washing.