Rule 260 vented loop for use in bilge pump installations to prevent siphoning of water back into boat from through hull. Features a one-way duckbill valve incorporated in the top of the loop allows air to enter the line when not in use, yet effectively seals as water passes through. Vented loops are anti-siphon safety devices for use with both manual and electric marine toilets installed below the waterline (static or heeled). Made of Marelon. Made of U.S.A.