I use Purcell prussiks on my rescue harness as my cows tails.
I find them more adaptable as I can prussik directly to a safety line or clip it as suits.
Just don't ask me how to tie the damn things.
benstevens21 Aug 2013
In reply to mpc: Sounds like you need to go to a caving shop. Online I know that both Hitch n Hike and Starless river sell dynamic rope by the meter (or do if you phone them) for cavers' cowtails