Boat Hatch White 4 inch 6 inch Round Non Slip Inspection Hatch w/Detachable Cover for Marine Boat Yacht --Made of ABS material, smooth finish,anti-aging, anti-corrosive,anti-ultraviolet. --Opening Dia: 4" (101mm); External Dia: 5-5/8" (143mm) --Opening Dia: 6" (151mm); External Dia: 7-4/5" (198mm) ; Cut Out Dia :6-1/3" (161mm) --Easy to install, Pre-drilled countersunk holes (Includes self tapping screws) Package list: 4x Boat Round Non Slip Inspection Hatch 32x Screws