This is the Large Bevel Gear for the Front and Rear differential for the HPI Savage 21. FEATURES: Steel Construction Gun Metal in color YOU WILL RECEIVE: One Large Diff Gear REQUIREMENTS: Item is a stock replacement part If mounting screw are needed, use HPIC0578 SPECIFICATIONS: Amount of Teeth: 43 teeth Width: 14mm (0.551") Overall Diameter: 44mm (1.723") COMMENTS: Works on both the front and rear differentials. NNA 2/24/03 ir/jxs &