I'd get some spare o-rings for it. Mine's never worked more than a couple of times before it starts leaking gas. I spoke with a ASG rep who said they had issues with certain batches. Some people I know seem to have no issue though. Hit & miss... Moved onto BFG's now anyway.
I had one and it worked perfectly for around 5 months of throws. They are great when they work but you do have to throw them quite hard to get them to go off