Designed for use with SCHALLER strap locks (not included), the strong brass construction of the Acousti-Lok provides the security you are looking for. With different Acousti-Lok designs to choose from, make sure you choose one that is compatible with your acoustic guitar's output jack. The Acousti-Lok is not designed for use with recessed or flush-mounted jacks. WARNING: Not compatible with TAYLOR guitars that have the AA battery EXPRESSION SYSTEM, but specifically designed for TAYLOR guitar models that operate with a 9 Volt EXPRESSION SYSTEM and have the corresponding Battery Box.