For insertion in concrete floors, spring loaded dust cover. These sockets are designed to accept the shoot of a flush bolt, and have a sprung central section which will depress when the flush bolt is engaged. When the flush bolt is disengaged, the sprung section will return flush to the top of the plate, thus stopping dust and dirt falling into the hole. Ideal for concrete floors in areas where a traditional flush bolt plate would gradually fill up and trap debris from the floor. Can be secured in place with glue or set in wet concrete. The slots in the side of the shaft aid secure fixing.Alias ID - bc06553