Mission Rubber MR56 64 Arc Wd Strong Back Calder Coupling

Product Description

The MISSION RUBBER MR56 64 ARC WD is a strong back Calder coupling designed to join 6-inch pipe to 4-inch pipe in no-hub drain, waste, and vent (DWV) systems. This coupling accommodates plastic-to-plastic and cast iron-to-cast iron connections, as well as cross-material transitions between plastic and cast iron pipe. Licensed plumbers install this fitting during new construction and repair work on gravity-flow drainage systems. The strong back design adds a rigid outer shear ring that reinforces the joint and resists lateral movement under load, making it a reliable choice in confined or high-stress installation conditions.

This coupling is used in residential and light commercial plumbing applications wherever a reducing or transitioning no-hub connection is required between 6-inch and 4-inch pipe. It is suited for underground, in-wall, and above-slab DWV runs. The Calder-style coupling is a widely recognized configuration in no-hub pipe joining, commonly specified on repair and retrofit jobs where pipe material or size changes mid-run.

Key Features

• Reduces 6-inch to 4-inch nominal pipe diameter in a single fitting
• Compatible with plastic-to-plastic, cast iron-to-cast iron, and plastic-to-cast iron transitions
• Strong back outer shear ring reinforces the joint and resists lateral shear forces
• Calder coupling design for no-hub DWV system installations
• Order increment of 1 for single-unit purchasing flexibility

Compatibility

Designed as an OEM-style no-hub Calder coupling for use with plastic and cast iron DWV pipe in 6-inch by 4-inch reducing configurations.

Installation Notes

Installation is performed by a licensed plumber in accordance with applicable local plumbing codes and the International Plumbing Code (IPC). Shut off water service and ensure the pipe run is drained before beginning work. Torque the stainless steel clamp bands evenly and in sequence using a hex driver or torque-controlled tool per the coupling manufacturer guidelines. Inspect pipe ends for burrs or damage before seating the coupling to ensure a proper seal.

Technical Specifications

• Pipe Size: 6 x 4 inches
• Connection Type: Plastic and Cast Iron x Plastic and Cast Iron (No-Hub Calder)
• Design: Strong Back
• Weight: 4.25 pounds
• UPC: 70288705764

Standard Information

• Brand: MISSION RUBBER
• Manufacturer Part Number: MR56 64 ARC WD