Turbo Rectangular Rock Grate. 17.5" x 28.5". The depth dimension (front to back) of a replacement rock grate should be within three sixteenths of an inch (0.1875) of the original parts depth to fit. The width of a grate is much less critical. A replacement can be a few inches narrower than the original and still be useful.
Turbo Rectangular Rock Grate
Enlarge View