Plastic push in Fittings (pneumatic fittings, push to connect fittings, one touch fittings) are made of nickel plated brass (thread) and PBT (body), stainless steel tube gripping claws, collars. Metric tubing O.D ranging from 4 mm to 16 mm, inch tube ranging from 1/8to 1/2 ; thread sizes range is from R, PT, BSPT 1/8 to R, PT, BSPT 1/2 and metric thread from M5 to M20.