GS-4 is a 2-band EQ with a built-in microphone control, a chromatic tuner and a nice colored LCD display. It’s easy for the user to control the sound of the microphone with the Blend knob. The position of the microphone is adjustable with a flexible goose neck. Moreover, it’s very easy to install into a guitar and the size is compact. It works with 2 pcs of CR2032 batteries and has automatic battery charge detection. Low battery message is displayed when the battery is getting low.