PVC Slip x Poly Tubing Compression Inserts will adapt PVC fittings to poly tubing. You must match the poly tubing outside diameter to the correct compression fitting size. Glue insert into PVC slip fitting using standard PVC glue. Once glued insert is dry, push poly tubing into the compression side for a secure leakproof seal.Orange - fits .250" OD poly tubingRed - fits .455" OD poly tubingGreen - fits .620" OD poly tubingBlack - fits .700" OD poly tubingBlue - fits .710" OD poly tubingGray - fits .940" OD poly tubing