【Compatibility】: Lock Cylinder is perfectly compatible with Thule roof racks, enhancing security for your cargo. Safeguard bikes, surfboards, canoes, kayaks, ski snowboard and racks cargo box etc 【Material】 : The lock cylindersinsertion port is made of stainless steel, the lock cylinder is made of zinc alloy, and the inner core is made of brass, closed design, stable, wear-resistant and anti-oxidation 【Package Includes】 : This 8 packs locks kit includes 8 lock cylinders, 4 keys and 1 mounting key(master key for adding or replacing lock cores) 【Easy Installation】 : This lock core replacement for Thule car racks system can be installed easily. Insert the master key into the lock core, then push the lock core into the cylinder, press and hold the lock core to pull out the master key, and then insert the matching key to turn and lock. Please refer to reverse order for disassembly If there are any problems with our lock cylinder, please contact us and we will definitely solve them as soon as possible 
When the lock cylinders on your racks are damaged or rusted, this is a security risk, just one key to lock, keep your gear safe. Install them in each one of your racks, bars, cargo box, etc. that way you only have to carry around one key. Makes things much easier. Cheaper than going local.

How to Removing a Lock Cylinder with a Master Key?
1.Unlock the component with the locking key
2.Insert the master key fully into the lock cylinder
3.Pull out the master key and cylinder together
How to Installing a Lock Cylinder?
1. Put the master key into the key slot in the lock cylinder
2. Push the lock cylinder fully into
3. Remove the master key and try the locking key