(2) 3/16 inch o.D. Pressure fittings are supplied for prressure connection with 1/4 inch push-on tubing. 3/16 inch i.D. Tubing is suggested for tubing lenghts up to 100 ft. 1/4 inch i.D. For tubing lengths up to 300 ft. 1/4 inch i.D. Tubing lengths up to 900 ft; service: air and non-conductive gases; output: 4 to 20 ma, 2-wire; max pressure: 10 psig; loop resistance 0-800 ohms