About the D'Addario Dual-Lock Strap Lock Set:
 
The D'Addario Dual-Lock Strap Lock provides a low-cost alternative to strap security for additional instrument protection. Without need of modification, the Dual-Lock clips onto your existing strap button to prevent your strap from releasing accidentally. Additionally, the Dual-Lock can be clipped onto your instrument cable, securing your cable to your instrument to prevent the plug from being pulled unintentionally from the input jack. D'Addario Dual-Lock Strap Lock–protecting your instrument and your performance.