Propeller Nuts used for through-hole or blind fastenings. Wings on the side of the barrel lock nut inside hole. Available as steel or as a die-cast zinc alloy for heavier nuts. Steel nuts available in lengths ranging from 1/4" to 7/16" and with either a 1/4-20 or 5/16-18 thread. die-cast zinc alloy nuts are available with a 3/8" long barrel and a 3/4" outside diameter head. Also available with either a closed end for visible use or an open end for interior use. Can be finished in normal plating colors!