Easy to install and use. Suitable for all kinds of guitars and basses. Each guitar needs two strap locks. One is at the above, another one is at the bottom. These metal strap locks can make your guitar's strap securely into the locking position. Installation Steps: 1. Screw in the pin on the guitar. 2. Make sure the pin is tightened, then lock the strap to the strap lock button. 3. Insert the strap lock into the fastening nut.