Senses tire pressure and transmits signal to the display unit. Compatible with all TireMinder Tire Pressure Monitoring SystemsTPMS for RV, Trailer, MotorHome, Truck, Car or Any Other Vehicle with Brass (Rubber) or Steel Valve StemsReplaceable Battery with 9-14 Month Lifespan (CR1632)Simply Replaces Valve Cap; Small, Light, and Out of the Way (0.5 OZ)