The "SG-4D" is 4-step Distortion Driver Unit. This is a built-in
distortion circuit for Electric Guitar or Bass that has been designed
to Simulate Historical Overdrive Tones. It is like having four of the
most famous Overdrive Pedal & Tube Amp Tones . It is very easy to
install with any Passive or Active pickups in your Guitar


Features :
Bypass Circuit system
Powered by 9 Volt batteries
About 1,000~2,000 hours ( 9 V Alkaline)