Amberlight Rectangular Rock Grate. 13 1/8" x 18 3/4". 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.
Amberlight Rectangular Rock Grate
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