Operates on water pressures above 11 p.s.i. Integral polypropylene check valve resists corrosive filtrates and fumes. The quick-disconnect hose fitting accepts 1/4" to 3/8 " I.D. tubing. Male thread faucet connection is 3/8" I.P. Maximum attainable vacuum is 27.4" (696mm) with flow rate of 1.5 gallons (6 liters) per minute. Supplied 12 per case.