8" ABS deck plate is sealed with a rubber O-ring for maximum watertightness and safety. Designed to be removable without the need for special tools, it features a single-start, non-jamming (no cross-threading), extra-strong, self-cleaning buttress thread. A patented back-up sealing wall maintains the plate's waterproof integrity even if the O-ring is lost or damaged. Clear plate with black flange ring. Use only 100% silicone caulk. Flange dia.: 10 1/8". Cutout dia.: 8 1/2".