Mm Manufacturing 203RF-8X4X5 90 Angle Register Boot with Flange

Product Description

The MM Manufacturing 203RF-8X4X5 is a 90-degree angle register boot with flange, designed for residential and light commercial HVAC duct systems. This fitting transitions supply air from a horizontal or vertical duct run to a floor, wall, or ceiling register opening. It connects to round duct and terminates at a rectangular register face with an integrated flange that seats flush against the finished surface. The 203RF-8X4X5 accommodates an 8-inch by 4-inch register opening and connects to a 5-inch round duct. Weighing 1 pound, it is a lightweight, field-installable component suited for new construction and retrofit applications.

This register boot is used in forced-air heating and cooling systems where a 90-degree transition is required between round trunk or branch duct and a rectangular floor, wall, or ceiling register. It is part of the 203RF series, which covers 8 common sizes for connecting to 5-inch, 6-inch, 7-inch, 8-inch, and 9-inch round duct. Typical installation scenarios include residential new construction, mobile home duct systems, and light commercial HVAC retrofits where sheet metal fittings are specified.

Key Features

• 90-degree angle configuration transitions round duct to rectangular register opening in a single fitting
• Integrated flange seats flush against finished floor, wall, or ceiling surface for a clean register fit
• 8-inch by 4-inch register face opening accepts standard residential register grilles
• Connects to 5-inch round duct branch line
• Lightweight at 1 pound for easy single-hand positioning during install
• Part of the 203RF series spanning five round duct sizes for consistent fitting selection across a job

Compatibility

The 203RF series is available in 8 common sizes for use with 5-inch, 6-inch, 7-inch, 8-inch, and 9-inch round duct connections. This specific fitting is designed as an OEM-style sheet metal register boot for residential and light commercial forced-air duct systems.

Installation Notes

Register boots are typically installed by HVAC sheet metal technicians or mechanical contractors. Power down the air handling unit and close the system dampers before cutting into existing duct. Secure the boot to the branch duct using sheet metal screws and seal all joints with UL 181-rated mastic or foil tape per local mechanical code requirements. Do not overtighten sheet metal screws into the collar seam, as this can distort the round inlet and create air leakage.

Technical Specifications

• Register Opening: 8 inches x 4 inches
• Round Duct Connection: 5 inches
• Length: 9 inches
• Width: 10 inches
• Height: 8.5 inches
• Weight: 1 pound
• Configuration: 90-degree angle with flange

Standard Information

• Brand: MM Manufacturing
• Manufacturer Part Number: 203RF-8X4X5