HPI Racing 102692 Bulletproof Machined Differential Bevel Gear Set, 29T/9T This Machined Bulletproof Diff Bevel Gear Set is our toughest diff set-up ever for the Savage monster truck line The ring gear and pinion gears are precision machined from high carbon steel and have stronger gear profiles for the ultimate in durability The 29T gear is machined to use the included "oversized" ball bearing for extra durability and efficiency