3mm steel core with plated finish protected with lacquer coating Removable Heavy Duty Steel Damper adjusts to turn airflow on or off Use "Knock Out Screws" or Optional Wall Clips (Sold Separately) to convert register to a wall register Listed sizes are the actual hole size the floor register will be inserted in to Damper Dimensions: 5-5/8" x 9-13/16" Outside Dimensions 7-3/8" x 11-13/16" These Victorian floor registers and vent covers have a plated finish. All Victorian floor registers come with an adjustable heavy duty steel damper. If desired, the metal heavy duty steel damper can be removed. You will be able to turn the 6 x 10 floor register vent covers into a sidewall vent cover by removing "knock out screws" (these are reverse threaded) and using screws provided or using wall clips (sold separately). Sizes given are the actual hole size needed for floor or sidewall vent cover to be inserted into. Actual faceplate will be larger. You will appreciate the simple drop-in-style installation.