1. "I"series couplings are interchangeable with INDUSTRIAL INTERCHANGE series couplings. 2. "I"series souplings have a full opening tubular valve for maximum flow and a bulit-in sleeve guard to minimize accidental disconnect. 3. The "I"series is available in 1/4" 3/8" 1/2"body size.Standard seal materials nitrile.See the coupling selection and ordering information guide at the beginning of section A and the fluid compatibility chart at the end of this catalog for optional materials .