Mm Manufacturing 400-9X8 Tapered Reducer 9x8 Duct Fitting

Product Description

The MM MANUFACTURING 400-9X8 is a tapered reducer duct fitting designed to transition between two different round duct diameters in forced-air HVAC systems. At 9 inches on the large end and 8 inches on the small end, this fitting allows installers to step down duct size without abrupt offsets that restrict airflow. Weighing 0.8 pounds, it is lightweight enough for single-technician installation in tight spaces. Licensed HVAC technicians and sheet metal contractors use tapered reducers like this one when balancing air distribution branches, connecting trunk lines to smaller runs, or adapting equipment collars to field-installed ductwork.

This reducer is suited for residential and light commercial forced-air applications where a smooth, tapered transition is needed between a 9-inch and 8-inch round duct section. The tapered geometry reduces turbulence and pressure drop compared to a straight-slip reducer, making it a practical choice for supply and return air trunk-to-branch connections. The MM 400 series spans 42 size combinations from 4 inches x 3 inches up to 24 inches x 22 inches, so multiple transitions in a single system can be sourced from the same product family for consistent fit and finish.

Key Features

• Tapered profile reduces turbulence and static pressure drop at the transition point
• 9-inch large end to 8-inch small end configuration for one-step diameter reduction
• Lightweight at 0.8 pounds for easy single-technician handling in attics, crawlspaces, and mechanical rooms
• Part of the 400 series with 42 size combinations for consistent fitment across multi-zone systems

Compatibility

Designed as an OEM-style tapered reducer for standard round duct systems in residential and light commercial forced-air HVAC installations.

Installation Notes

Installation is typically performed by a licensed HVAC technician or sheet metal contractor. Power down the air handling unit and confirm the system is de-energized before cutting into or modifying existing ductwork. Secure the reducer with sheet metal screws and seal all joints with UL 181-listed mastic or foil tape in accordance with local mechanical codes. Avoid over-compressing the fitting during installation, as deforming the tapered section can restrict airflow and increase static pressure.

Technical Specifications

• Large End Diameter: 9 inches
• Small End Diameter: 8 inches
• Length: 9 inches
• Width: 9 inches
• Height: 7 inches
• Weight: 0.8 pounds

Standard Information

• Brand: MM MANUFACTURING
• Manufacturer Part Number: 400-9X8