if you go with the SMC rings use the desending rings and not the descending/rigging rings
not these: http://www.rei.com/product/799957/sm...escending-ring
i have used both type with a sliding ring suspension and find that the round cross section rings are much easier to slid up and down the lines, plus they are cheaper and liter in weight. have not used either with a webbing suspension...
just my 2¢