Demaree Boat inflatable boats, Inc. fabricates the sponson (inflatable collar) for the Naval Special Warfare 11M RIB at our plant in Maryland. The sponson component consists of two inflatable tubes joined at the bow, a bow strap, and a bow sailboat cover to reinforce the joint. A summary of the options for the sponson system tube is outlined below. The prices are for one tube - either starboard or port.