Overview: Great choice for 1/10 Scale 4WD models looking for a high RPM motor upgrade running up to 3S * (12.6v) power. Low cog 4-pole rotor design, CNC machined aluminum housing, insulated high purity copper windings, high-quality alloy steel 5mm output shaft, and high-precision bearings for high durability and smooth rotation. Preinstalled with 4mm gold plated bullet connectors for easy installation. Perfectly matched for the Firma 130 Smart ESC. *Will work with the 85A Firma ESC, but only for 2S power. Features: Perfect upgrade for brushed 540- and 550-size brushed motors with the same diameter and mounting pattern (vehicle must accept pinions with a 5mm bore) High-quality 4-pole sintered rotors Includes 4mm gold plated bullet connectors Precision ball bearings and hardened steel 5mm shaft SafeD-5 Pinion compatible