This is a carabiner-style key holder with a retractable reel. The wire is made of metal, and I personally use a similar one every day at work, and it's very durable. =Personal Experience= I used to use a reel-type key holder from a 100-yen shop, but the winding strength was weak, and it wouldn't retract with 3-4 door keys. Also, the wire wasn't metal, so it would break after about two months. However, this type has solved those problems.