I've had the same two sets of Kanu Locks for probably 6 years now.
Because I can't store boards at home, they are on the roof of the car 24 / 7.
The actual locks are pretty crappy, but I think I have actually locked them about 5 times.
Well the locks are OK, the keys are tiny and crappy, and care is needed to make the locks work without breaking the keys.
Security of being able to lock the straps nice at times, but in general, they are just a good quality, strong, easy to use tie down.
The extra weight in the strap makes them easy to throw over the car.
www.kanulock.com.au/