In reply to Stephen:I have been using one made by Simond,it has two karabiners which are joined together by two bars.It works really well and holds quite a few screws.Only place I've seen them sold is Hitch'n'Hike in Bamford,near Hathersage,cost around 16 quid,even cheaper from the Mountain Equiptment Co-op in Canada.Hope this is of some use to you.Also got a BD one as well,again works pretty good aswell.
