Music Nomad's patent pending Acousti-Lok is a strap lock adapter that adds the safety & flexibility of using strap locks to your acoustic guitar without permanently modifying it. Designed to be used with SCHALLER style strap locks (not included), Acousti-Lok's strong solid brass construction gives you the security you have been looking for. Acousti-Lok was not designed to be used on recessed or flush mount jacks.