No.17-509 standard tire gauge. 10 to 50 pounds - Use for passenger cars, light trucks and vans. Calibrated two sides 10- 50 PSI in one pound unit and 70-350 kPa in 10 kPa units. No.17-519 truck tire gauge. 20 to 120 pounds - For all higher pressure applications on lightweight trucks (1/2 to 2-1/2 tons), step vans, pickups and air shocks. Calibrated two sides 20-120 PSI in two pound units and two sides 160-880 kPa in 20 kPa units.