Fitted to a Fender Jazz Bass. Main advantage is they are noiseless. The tonal range is no greater than the original pickups. The cavity really does need deepening to fit the battery or preferably fit a battery box, which will allow you to change the battery without unscrewing the control plate. Should also be supplied with new foam strips to get the pickup height set correctly. Can be fitted with 2 batteries, although I found 1 perfectly loud enough.