Flexible compression ring that seals a smaller new pipe into a larger cast iron hub or service-weight bell. The donut wedges into the hub annulus, the pipe is pushed through the center bore, and the elastomer squeezes against both surfaces to form a watertight DWV joint without mortar, lead, oakum, or cement. Ideal for tying a new 3" PVC or ABS stub into an existing 4" cast iron stack during a remodel, partial repipe, or fixture relocation where the old hub stays in place.

• Fits a 4" cast iron / service weight hub
• Center bore sized for 3" PVC, ABS, copper, or galvanized pipe OD
• Flexible PVC compound molded as a one-piece compression ring
• No mortar, tar, cement, lead, oakum, or torch needed
• Absorbs ground movement and minor pipe deflection without breaking the joint
• Approved for DWV (drain, waste, vent) service
• Connects dissimilar materials - cast iron hub to PVC, ABS, copper, or galvanized stub
• Resists infiltration and exfiltration when properly seated
• Manufacturer Part Number: P44U-305

Common Uses: Tying a 3" toilet branch, kitchen / laundry branch line, or vertical riser into a 4" cast iron main drain hub. Frequent on second-story bathroom remodels where the 3" toilet drain ties into a 4" building drain stack stub.

Install Tip: Clean the inside of the hub and the OD of the pipe with a wire brush so the elastomer seats against bare metal and bare pipe, not rust scale or old joint compound. Lubricate the donut bore and the pipe spigot with plumber's silicone or soapy water (never petroleum grease - it swells the PVC compound), seat the donut into the hub flush with the hub face, then push the pipe straight through with steady pressure until it bottoms out. Twisting the pipe during insertion tears the bore; if it won't push by hand, add more lube rather than forcing it.

Note: Donut joint sealers are for non-pressure DWV service only. Do not use on pressurized water, gas, steam, or compressed air lines.