Wilson special tools are required for mounting the cello C pickups correctly. The 4.90 mm precision drill and the special handmade 4.99 mm reamer are required to obtain the maximum output of sound from the 5.01 mm cello piezo pickups. A wooden stick is required to help removing the pickups from the bridge. Please note: Special tools are included when purchasing type C pickups. Set contents: Drill and reamer to prepare the holes, as well as a wooden stick for removing the pickups from the bridge correctly.