American Aldes Dryer Lint Trap - for drywall installation.  Can be ceiling or wall mounted.  4" Duct Collars on each side of trap.  This secondary lint trap is intended for use when required in a Dryer Booster Fan application,  as noted in the Dryer Booster Fan installation manual. Additionally, this secondary lint  trap can be used in Dryer Booster Fan applications where excessive dryer lint generation is likely.This secondary lint trap is not intended for use without a Dryer Booster Fan, unless the application is approved by the dryer manufacturer and/or the local building inspector.