Lids hinge open, so you never lose the lid. A simple twist of the handle opens or closes the hatch. The hatch does not have to be held down against a flat surface to seal. This allows the hatch to seal even if the lid is paritally open or tipped. Available in 6” and 8” diameters. Retrofit kits include gaskets and 2 ea #8031130 screws for the 8”.