These are intended for use on basses already equipped with a preamp, or a build that is planned to incorporate a preamp. The simple design, and easy access allows you to use no battery terminal clip to distribute 9v or 18v D.C to your onboard preamp or active circuit. Contacts inside the box, and generous wiring allow installation,and battery changes to be painless. Dimensions are provided below for both models. If you require a template to aid in routing for either battery box please visit our routing template page Here.