Unlike "jam" nuts that simply bind one set of threads against another to create a "lock", Back Stop is a unique double-nut system with a floating collar between the nuts that locks down the position of the reel seat hood without tightening the hood further against the reel foot. This unique "floating collar" actually tightens when the hood nut attempts to loosen, and generates a pushing force against the hood nut. Completely eliminates reel foot loosening. Available in extended nut (LOS16/AN) or a hidden thread collar (LOK16/AN) similar to the KDPS hood.