An alarmed disc lock, that's easy to use, doesn't go off inadvertently and is as loud as a bike-borne alarm. Designed for one-handed use, the RS3 snaps open when unlocked and clamps closed easily. The alarm won't go off unless it's clamped to something and it's rubber-wrapped for a decent grip even when wet. It's earned a hard fought place in my travelling rucksack-Khal Harris