Wilson special tools for violin are required for mounting the V pickups correctly. The 3.40 mm precision drill and the special handmade 3.49 mm reamer are required to obtain the maximum output of sound from the 3.50 mm piezo pickups. A wooden stick is required to remove the pickups from the tight fit in the bridge. Please note: Special tools are included when purchasing type V pickups. Set contents: Drill and reamer to prepare the holes in the bridge special key for adjusting the volume, as well as a wooden stick for correctly dismounting the V pickups from the bridge.