In reply to Matt Schwarz:
Yep, 60cm is absolutely my favourite length (carried tripled, but frequently placed to use the full extension), followed by 30cm (which can still be carried doubled) if you need shorter ones! So I took my 10cm draws (from a mixed pack) apart to 'borrow' the krabs for longer ones, and am tempted to do the same for the 15cm (keeping just the 20cm as bought), and made up my new 30cm ones with O-rings to secure the rope-end krabs.