Seaview SV101V Vault Drain Plug, black. Engineered to screw right into the existing 1/2" NPT brass or stainless transom garboard. Triangular ergonomic cap - no tools required. NPT backup o-ring for a water tight fit. Approved for all marine environments, including salt water. Floats if accidentally dropped in the water. Manufactured from glass fiber reinforced ABS to increase strength and flexibility. Increases fatigue endurance, resistance to extreme temperatures and abrasion.