The Shadow SH Four Plus is a four band EQ with volume control. It has a phase invert switch to minimize feedback. With the EQ-Shape switch you can choose linear or "V" shaped frequency in the middle position of the tone controls. The 9V battery is under the preamp and is easy accessible by lifting the preamp out of the case. Fastening screws are fixed into plastic plugs - not into the wood. It is totally shielded and has zero hum.