GENERAL WIRE 3″ FLOAT MODEL FLOOD GUARD – 3F FLOOD-GUARD OPERATES LIKE A CHECK VALVE TO SEAL OFF WATER BACK-UP CAUSED BY OVERLOADED SEWERS. WATER FLOWS NORMALLY THROUGH THE DRAIN UNTIL THE SEWER BEGINS TO BACKUP. THEN THE FLOOD-GUARD FLOAT RISES TO SEAL OFF THE DRAIN OPENING UNTIL THE WATER RECEDES. A SCREWDRIVER AND A COUPLE OF MINUTES ARE ALL YOU NEED TO INSTALL A FLOOD-GUARD. ONCE IN PLACE, IT CAN PREVENT PROPERTY DAMAGE AND A VERY MESSY CLEAN-UP JOB. GASKETS ARE MADE OF MOLDED RUBBER, AND ALL METAL PARTS ARE PLATED OR STAINLESS STEEL.