This product is a genuine Traxxas long RPM sensor designed to measure motor speed for use with Traxxas telemetry systems. It features a 3x4 mm mounting size and extended sensor length for proper alignment and accurate signal detection. This sensor allows real-time RPM data to be transmitted to compatible Traxxas telemetry receivers for performance monitoring and tuning. It is compatible with telemetry-equipped Traxxas models including Slash 4x4 VXL, Rustler 4x4 VXL, Stampede 4x4 VXL, Hoss 4x4, and E-Revo VXL 2.0 when used with the appropriate telemetry hardware. It is an ideal replacement for damaged sensors or for restoring full telemetry functionality.