This is Novak's 5mm Mod 1 Steel Pinion Gear 3-Pack (12T/13T/14T) (#5121). These hardened gears are available in packs of three gears, allowing drivers to experiment with gear ratios. These are the same high-quality gears offered individually, but in a money-saving combo pack!
Novak's Mod 1 Pinion Gears feature a high-strength hardened steel construction and are precision machined. These gears are compatible with Novak’s Ballistic 8 Brushless Motors (#3801-3802), Ballistic 550 (#3504-3507), and other motors with a 5mm output shaft. Each gear includes a set screw.