CompatibilityThe core locks perfectly fit compatible with all thule products. thule products use the same lock cylinder, such as bike rack, roof racks, ski rack, cargo box, cross bars, towers, kayak rack etc. The package includes 4 lock cores, 2 keys and 1 universal master key compatible with adding or replacing lock cores. _x000D_ _x000D_ Built to LastThe lock cylinders are made of high-quality aluminum alloy material. The inner core is made of brass. It is corrosion and wear resistant. It is a thule one key system worth buying. ATTENTION PLEASE!!! If using this around salt water, spray silicone inside the locks. _x000D_ _x000D_ Safe & SecureWhen the lock cylinders on your racks are damaged or rusted, this is a security risk that will require you to replace them with new ones, thus deterring theft. Perfect if you have more than one thule product. Install them in each one of your thule racks, bars, cargo box, etc. that way you only have to carry around one key. Makes things much easier. Cheaper than going local. _x000D_ _x000D_ Easy to InstallInstall or replace the lock cylinders on your thule products in a few easy steps. To replace an existing lock core simply unlock it and use the included master key to remove it. Once the existing core has been removed, pop in the new One-Key System lock.