Top critical review
Not particularly tough, but would deter a casual thief
on May 1, 2013
I'm pretty sure you could break these open quite easily with any old blunt object you might have handy, but I definitely can't force them open using just my hands, so for their intended purpose - preventing snoops and thieves while travelling, where your bags are generally near you anyway - it works well.
The one notable flaw I found was that they contained a substantial amount of metal filings, fresh out of the box. I was eventually able to flush these out using a water jet (which might not be good for the internals, but an air blower wasn't enough). If you're just using these on regular luggage that's probably fine - I expect the filings will fall out with use, in time - but in my case it was on a camera bag, and the filings were just the right size to get into lenses and camera bodies and wreak havoc.