The invention is for a solid body type guitar having a pickup selector switch located closely adjacent to the volume controls. The invention is a specially developed pickup selector switch tip knob having an extension arm which is contoured to conveniently fit the human finger for easy manipulation of the pickup selector switch. The contoured extension arm can have one or both sides contoured to accommodate easy pickup selection from either direction with the guitar player's hand. The invention can be mounted on the pickup selector switch post such that the extension arm is facing either toward the guitar strings or away from the guitar strings.