A flat buckle that doesn't rub you the wrong way. This slim buckle works with 3/4" (20 mm) binding tape. We use this on the neck of our sleeping bags, and on some clothing items where a protruding buckle would be in the way. The male side adjusts, and the female side does not. The buckles will break under high tension so they are best in applications where they aren't under a lot of stress.
