Heavy semi-finished hex nuts are slightly larger and thicker than finished hex nuts which helps distribute the load over a large area. They are a 1/8 larger across the flats than a standard hex nut in all sizes, requiring a 1/8 larger socket or wrench to install. Load strength is far higher than the standard hex nut. 18.8 stainless steel fasteners have good outdoor and chemical resistance and may be mildly magnetic.