I use 550 7 Strand Paracord. I make these and bracelets for my shop. freehippie.etsy.com My husband is a volunteer fire fighter and told me that the regular bracelets and keychains just wouldn’t work for him. So I searched the web and low and behold if my favorite knot expert didn’t have JUST the course I needed. So now my husband has a keychain (his is 20 feet of paracord and attaches to his suit) and that makes me feel a little better.