Pair of Schaller Black Security Guitar and Bass Guitar Strap Locks.
The lock mechanism attaches to your strap. You must use the Schaller strap button included. Pull the knob on the front of the lock and a plunger moves allowing the lock to slide around the Schaller button. Release the knob, the plunger springs back and into the center cavity of the Schaller button. Your strap ain't going nowhere now!