Use for 3 months only. Never touch rocks. Always dry after each use. I believe 2-3 of them never been use a single time. 58$ each screw include shipping with paypal donation. I would like to sell the whole set or 6-7 screws. See close up of the teeth for all screws. Last picture is the worst screw in the lot because its rust but the teeth is near perfect condition like all others screws.