Flush Rim grilles provide two way diffusion and are the preferred style for prefinished hardwood floors where an architecturally smooth installation is required. These grilles "drop" in to a pocket routed in the finish flooring. Each vent is 3/4" thick with a standard rim that is 1" wide by 5/16" thick. Custom rim thicknesses are available upon request (20% upcharge). Adjustable dampers are available for all standard sizes.