How to Use: 1: Place the drill bit in the center hole of the hexagonal key and then place both in the center of the alternator clutch. 2: Fix the drill bit, rotate the spline nut clockwise to unlock the alternator clutch pulley, or reverse direction to lock the new clutch Specification: Item Type: Alternator Pulley Drill Bit Kit Material: Steel Hex Part Length: Approx. 17mm/0.67in 33 Teeth Spline Part Length: Approx. 30mm/1.18in Spline Outer Diameter: Approx. 20mm/0.79in Spline Inner Diameter: Approx. 12mm/0.47in Drill Bit Length: Approx. 75mm/2.95in Fitment: Replacement for Bosch Alternators Replacement for Replacement for Benz Replacement for Fiat Replacement for Seat (Fits for any clutch pulley with 33 teeth spline hole) Package List: 1 x Drill Bit1 x 33 Teeth Spline