I still have some Sampo swivels that are 40 years old. Still strong, bit discolored. Don't know all the details about the steel, but they aren't rusting, and holding up well. Most of my Peregrines jump in the bath pan around 5 days a week, less in the winter, but catch a lot of ducks. Swivels are subjected to a lot of water and blood, haven't had any failure. I really like the barrel swivel setup with the leash. BUT, have had a lot of problems with them. They will freeze and stop turning, also, bird shit will clog them up and then again, they don't want to turn!