The Dwyer 476A Digital Manometer measures low pressures from -20 to 20" w.c. with ±1.5% full scale accuracy. Designed especially for the HVAC contractor, the Model 476A-0 can be used to set gas supply pressures, verify pressure switch operation, adjust regulators, check pneumatic systems and computer peripherals. The rugged, handheld unit is constructed with an extruded aluminum case for exceptional durability.