Review on High Security Bike U Lock with Mount, Heavy Duty Combination - 14mm Lock for Road, Mountain, Electric, Folding Bicycles - Includes 4ft Flex Bike Cable for Added Protection by Richard Payne

I didn't use bolt cutters to see what was going on but this bike lock seems very strong and secure. I love that the lock is on the bottom of the crossbar which means the bolt comes straight out either side making it easy to attach and detach, you don't have to loop through an end to secure it. I also like that it comes with a separate cable loop so you can lock the wheel and then thread the cable around any size bar (without having to use a U-lock on both, which can be tricky in certain circumstances). It also comes with a bracket that you can attach to your bike's frame for easy carrying of the lock (although it also doesn't fit the tether loop that you have to carry any other way. Good value for a sturdy one Bicycle). Security system.