Pneumatic Day/Night Thermostat, Direct Acting Heating, Two Temperatures, 3 Pipe, 59-90 Degree Day Setpoint Temperature Range, 50-80 Degree Night Setpoint Temperature Range, 13 Psi Day Changeover, 18 Psi Night Changeover, 2-10 Degree Throttling Range, Wall Mount, 0.011 Scfm Airflow Usage, Bimetal Sensor Element, 25 Psi Maximum Operating Pressure, Has Secondary Branch Line