The Yakima 12 Pack SKS Lock Cores allow you to use just 1 key to lock/unlock all your Yakima car rack system components. SKS stands for "Same Key System" which means that the key that comes with this pack of locks will work on every single one of the locks. No need to carry 12 different keys! If you are anticipating growth in the amount of rack equipment you own, this pack will provide you with locks for future rack equipment expansion! The pack also comes with a blank key that allows you to insert or remove the lock cores into/from your rack components.