Mm Manufacturing 641R6-8X4X4 Insulated Register Box

Product Description

The MM Manufacturing 641R6-8X4X4 is an insulated register box with flange designed for use in residential and light commercial HVAC duct systems. This box connects supply ductwork to a floor, wall, or ceiling register and provides an insulated transition point that helps reduce heat loss and condensation at the register opening. The R-6 insulation value makes it suitable for installations where energy code compliance or comfort performance is a priority. At 1.8 pounds, it is lightweight enough for single-technician handling during installation in tight plenum or joist-bay spaces.

This register box is used in forced-air heating and cooling systems where a rigid or flexible supply duct terminates at a register grille. The 8 x 4 x 4 inch configuration fits a standard 8-inch-by-4-inch register opening and is appropriate for residential new construction, retrofit duct work, and light commercial HVAC applications. HVAC installers and sheet metal contractors typically use this box when running supply branches from a trunk line or air handler to individual room registers.

Key Features

• R-6 insulation value reduces heat loss and limits condensation at the register boot
• Integrated flange provides a positive register grille mounting surface for a clean, secure fit
• 8 x 4 x 4 inch throat size fits standard register openings of that dimension
• Lightweight at 1.8 pounds, easing single-person installation in confined spaces
• Compact package dimensions of 10 x 6 x 6.75 inches for efficient jobsite storage and transport

Compatibility

Designed as an OEM-style replacement or new-installation register box for residential and light commercial forced-air HVAC duct systems requiring an 8 x 4 x 4 inch insulated boot with flange.

Installation Notes

Installation is typically performed by a licensed HVAC technician or sheet metal contractor. Power down the air handler or furnace at the disconnect before beginning any duct work. Secure all duct connections with mechanical fasteners and seal with UL 181-rated mastic or foil tape per local mechanical code requirements. Do not compress or puncture the insulation layer during handling, as damage reduces effective R-value.

Technical Specifications

• Throat Size: 8 x 4 x 4 inches
• Insulation Rating: R-6
• Package Length: 10 inches
• Package Width: 6 inches
• Package Height: 6.75 inches
• Weight: 1.8 pounds

Standard Information

• Brand: MM Manufacturing
• Manufacturer Part Number: 641R6-8X4X4