This is the Hitec Magnetic RPM Sensor. FEATURES: For the Hitec #55845 & #55830 telemetry systems Compact design Two mounting holes on the sensor INCLUDES: One sensor Mounting hardware Three magnets REQUIRES: Installation following the manual SPECS: Wire Length: 8-1/2" (216mm) Sensor Width: .16" (4mm) Sensor Length: 1.20" (30mm) Sensor Height: .36" ( 9mm) Magnet Diameter: .11" ( 3mm) Magnet Height: .06" (1.7mm) ajw 11-22-10 ir/jxs