DP transfer grilles ensure air circulation between rooms and are mounted in interior doors. This solution is especially relevant for doors under which there is no clearance. The minimum thickness of the door leaf for 4409DP is 25 mm, for 4513DP - 33 mm. The kit includes two grilles; they are inserted into the door on both sides, connected to each other in grooves and secured with self-tapping screws or glue.