The Yakima SKS "Same Key System" Lock Cores allow you to use just 1 key to lock/unlock all your Yakima car rack system components. Add up the number of lockable items you plan to purchase now or in the future and select as set of cores in two to twelve packs. It comes with two numbered keys and a control key for installation and removal of cores. The cores have the key number engraved on the side. Most Yakima carriers and accessories are SKS lockable directly to the rack or lockable with an Accessory Lock Core Housing. For additional security you may want to check out the SKS Locking Cable.