USI Electric Metal Duct Adaptor Replacement Part for Bath Fans, 4-Inch Duct (BF-A4)
Availability:
Sorry, this item has been DISCONTINUED.
- Metal Duct Adaptor Replacement Part is designed for use with USI bathroom exhaust fans.
- Connects to 4-inch ducts.
- Use this part to replace the worn or broken duct adaptor on your bath fan.
- Adaptor can be used with models BF-504, BF-504L, BF-504LF, BF-504BA, BF-704, BF-704L, BF-704LF, BF-704LH, BF-704HB, BF-704BA and BF-704L.
- Bathroom exhaust fans by USI Electric combine high function with practical design to keep air moving and effectively pull out moisture.
USI Electric Metal Duct Adaptor Replacement Part for Bath Fans, 4-Inch Duct (BF- Product Description
The USI Electric BF-A4 Metal Duct Adaptor Replacement Part is designed for use with USI bathroom exhaust fans that connect to 4-inch ducts. Use this part to replace the worn or broken duct adaptor on your bath fan. This adaptor can be used with models BF-504, BF-504L, BF-504LF, BF-504BA, BF-704, BF-704L, BF-704LF, BF-704LH, BF-704HB, BF-704BA and BF-704L. Bathroom exhaust fans by USI Electric combine high function with practical design to keep air moving and effectively pull out moisture. Return your bathroom to a normal humidity level and prevent mold, mildew and odors from taking over your living space with a USI Electric bath fan.
Product Specs
UPC:
042741507042
MPN:
BF-A4
Category:
5
4
3
2
1
1 customers recommend this product
USI Electric Metal Duct Adaptor Replacement Part for Bath Fans, 4-Inch Duct (BF- Reviews
Jason Sirko
April 29, 2026
Just What I Needed
I recently purchased the USI Electric BF-A4 4-Inch Duct Adapter to upgrade my bathroom ventilation, and the difference in performance is outstanding. Moving from a standard 3 inch setup to this 4 inch adapter has noticeably increased the airflow and reduced the noise level of my exhaust fan. The adapter is made of high-quality, durable plastic that feels much sturdier than generic alternatives. It snapped onto my existing USI housing effortlessly, providing an airtight seal that made the ducting process incredibly simple. The built-in damper works perfectly to block outside drafts, making it an essential, high-value part for any professional-grade bathroom repair.