three-way plastic side wall/ceiling register in white 10"w x 8"h for duct opening (outside dimension is 12"w x 10"h) hbw <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 12”wide and 10”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 10”wide and 8”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 10”x 8”.</li></ul>