This ten pack of plastic locks with individual serial numbers is very useful for locking chastity belts. They're compatible with the CB-2000,CB-3000, CB-6000s, CB-300 Curve, and more!. The individual serial numbers ensure that the wearer is wearing the same lock that they started with. It also allows the non-metal chastity devices to go through metal detectors. They can even be used online through webcams. These are a great cock control accessory.