Flush Mount Grilles are typically used with new flooring installations, but may be installed in existing flooring (time and patience required). Typically, a frame is ordered with the flush mount grille. The frame sits on the subfloor, and the grille drops into the frame for easy access to the duct for cleaning. Both the grille and frame are flush with the existing floor. All grilles are sold unfinished to offer the versatility of adding the stain and/or finish of your choice.
The pictures shown above are just a sampling of sizes and wood species available.