The purpose of the kayak lock is to keep your kayak locked down to a vehicle or storage system to protect it from theft or damage. Kayak locks also offer a bit more protection by securing the kayak to a rack or to the top of your vehicle.
Several companies make kayak locks. Each lock comes in different lengths for different sized kayaks and vehicles. Some locks come with adjustable length cables to make sure you can tightly tie down the kayak
Kayak locks have steel cables, making it more difficult for the cable to sheer from someone trying to cut it or from wear and tear. Most companies make replacement cables so you can just replace a cable and not the whole lock if you need to.
Kayak locks come with the ability to put in a combo where the cable ends in a ball or T-shape that fits into the lock. The combos come with factory settings but give you the option to input your own personal combination to unlock the kayak lock.
Kayak locks are wrap-around and tie-down locks. Some can attach directly to racks and trays on a car roof, and some can attach to small openings with little space.