HBW sidewall/ceiling register is made of stamp faced steel and powder coated in white. It has built-in damper to control air flow. There are two screw holes on each side of the register to fix on the surface of wall or ceiling. Sidewall/Ceiling Register Measurement Outside overall dimension is 15.75” in length and 7.75” in width Duct opening – a hole that holds the duct neck to allow air to come out from HVAC system. This register fits in a duct opening of 14” in length and 6” in width. Size Selection Guide Measure the size of the air duct opening(the size of the “hole” ) . Measure the duct opening Match the duct opening size with the listed size of 14” x 6”.