Made out of heavy duty plastic, these bags are designed to hold shape and stand up on their own. After a day of boating, cleanse your engine with fresh water. Place the flush bag careflly under the skeg and then attach the guide strap which goes over the top of the cowling. Fill the bag until the water passes the intake inlets and idle your engine in neutral for 5-10 mins. Finally, unscrew the drain plug and let the water flow out.