TRAXXAS Telemetry trigger magnet holder, center differential/ magnet, 5x2mm (1)/ 3x8mm BCS (3) (for use with #6814 center differential) 38-6539 Description: Add RPM and speed telemetry to your 4X4 vehicle equipped with the 6814 center differential. Includes magnet and 5x8 mm screws (3). Real-time telemetry requires a TQi radio with Traxxas Link™ Wireless Module and the free Traxxas Link app for your mobile device. Does not fit other center differentials Accessory part for these models: Rustler 4X4 Slash 4X4 Ultimate Ford Fiesta ST Rally Slash 4X4 VXL Slash 4X4 Stampede 4X4 Unassembled Kit Stampede 4X4 VXL Stampede 4X4