Please Note: Gray PVC insert fittings are made of the same substances as schedule 40 and schedule 80 PVC are made of. This means a durable long lasting fitting. Insert fittings are normally used with flexible pipe, hose or tubing. Simply slip the barbed insert tip all the way into the end of the flexible pipe, hose, or tubing. Multiple sharp barbs provide a tight grip on the flexible materials to create the seal. It is recommended to clamp over the barbed fittings to provide a reliable leak-proof seal. Proper clamping technique is to place the clamp directly over the barb area and tighten. For additional size specifications see the Spec sheet linked to item page above. Use this PVC Barb Tubing Reducing Tee insert fitting to connect three sections of tubing together when one section of tubing is a different size.