<ul></ul><b>HBW plastic sidewall/ceiling register is made of ABS plastic in bright 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. </b> <ul></ul><b>Sidewall/Ceiling Register Measurement</b><ul><li>Outside overall dimension is 9.75”wide and 6”high </li> <li>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 8”wide and 4”high.</li></ul> <b>Size Selection Guide</b><ol><li>Measure the size of the air duct opening(the size of the “hole” ) . </li><li>Measure the duct opening </li> <li>Match the duct opening size with the listed size of 8”x 4”.</li></ul>