I bought it to me 2 sets. Each 1 set for my bike and my girlfriend. The Verarebitung is fine, no Gratte and nothing. The handling is easy and simple and in a short time you have the existing tensioner exchanged it here. Of course, nothing offers a 100% protection, but for most casual thieves, it should be enough. You need a special key that can be set, however, by way of purchase of such sets. There can be at least not with an Allen key, also open any 5.5. I guess for the price a good protection! The manufacturer of probably TransX.