This replacement cap for the popular and cheap HD 201 headphones allows you to use a generic Bluetooth (www.bit.ly/BTHD201) headphone adapter inside your headphones. The mod requires you to shorten and run your headphone wires internally. You do not need to disassemble the Bluetooth adapter! Uses the stock screw locations. Do not try and screw the stock screws all the way in, turn in a couple of turns and then back out til you are able to easily thread them all the way in. Sorry for the potato quality pictures!