This unit has a built in speaker. Attaching it to your upper chest / shoulder you can hear your metal detector audio tones without using headphones. Also has the option to plug in your headphones so you can operate without being attached to your machine. Allows you to listen to audio wirelessly for greater freedom of movement. More than one WM 12 can be connected to GPZ 7000 for group training or dual-mono immersive sound.
