I recently bought one of the XENA Alarmed Disc Locks to increase my bike security. Looked good in the shop, and (apart from deafening me when I first set it up) attached to the bike disc no problem. I wanted an alarmed lock for two reasons: 1. Additional deterrent 2. So I can't ride off without first taking the lock off! Anyway, for a day or so all was well, apart from a couple of false alarms at night - I put these down to our curious 50kg dog wandering around my bike. HOWEVER After several more days, it became clear that the false alarms had nothing to do with the dog. The instructions said to put the alarm in the 6 o'clock position on the disc to lower its sensitivity - no improvement. Yesterday I came home to find it going off in the driveway and there was definitely no-one around. This, together with a few terse words with my neighbours, led me to take it back. AND THEN do you think the shop would accept that it was a faulty design? No. They even rang the distributor and I was advised to leave the lock there, and come back in a few days to see what the distributor thought. So what if my bike is pinched in the meantime? No answer. Anyway, after some further terse words, I insisted on my money back, and finally got it. SO If you like terse words, buy one. If you don't, then just get the regular non-alarmed one, and put an extra chain on!