This is Xtra Speed Steel #45 Helical Spiral Gear & Pinion Gear Set 30T / 8T For Axial SCX10 II. Beefen up your rigs that run Axial's SCX10 II axle with this set of Heavy Duty Helical Bevel Gear Set from Xtra Speed! Helical gears means that your transmission will run more efficient and at a quieter sound level compared to traditional gears.