In reply to Flinticus:
Petzl OK are good (or DMM Ultra O, etc), but I suggest *not* a screwgate, go for self locking.
An oval quicklink nipped up tight with a little adjustable spanner (Maillon Rapide, etc) is cheap and dependable
There is a magical product that can be retrofitted to krabs, it's called finger tape, put some straight across the middle from gate to spine, to divide into upper and lower halves, twice round should do it. The only consideration is if you have one that doesn't leave a sticky residue on the krab.