Tough aren't they? Decided to throw away my original Z-One which I was never entirely sure had hit the ground but didn't use after my off in '02 - it going mouldy kind of made it necessary. Still, decided to try beat it up a bit so no one would be tempted to use it - a 10 minute assualt with hammer & pry bar resulted in rather disappointing results. I managed to hole it with the pry bar quite nicely, but it still didn't go all the way through - and the hammer just created cracks in the shell. I'm quite pleased to know that I can get a whack to the head with a pry bar and potentially be okay :-)