46" Long x 3" Thick Super Duty Steel Hidden Mantel Hardware - for 48 to 57 inch Mantel - Manufactured in USA Hidden mantel hardware, engineered to support mantels that are 3 1/2" thick or greater, and from 7" to 14" deep. The original patented bracket Made to install on masonry, sheetrock, plaster, and paneled walls Supports a maximum distributed load up to 200 lbs., when installed correctly Screw holes are set 1" OC from each end and continue 4" OC down the length of the hardware. Countersunk screw holes are 3/16" OD A set screw hole can be drilled in the outside rods to screw the mantel to your hardware. You can also glue the mantel onto the hardware with silicone. Both are equally effective, glue is the easiest method