Wow,I thought I could actually add something to the discussion,but I'm more confused than ever. Perhaps I'd misunderstood forum dialoging from the past, but I remember that the general consensus was that color is used as a U.V. blocker,and the drawback to this addition is a reduction in elasticity. However now, all I really care about is which one packs the biggest, baddest punch! I can buy fresh black 5/8in. for $2.00 per ft.(bulk) here in town. What I really want is 21mm.

Certainly, we all want to improve the overall performance of our guns, (and I'll admit that I'm an equipment junkie) the fact is that slings are supposed to be used up. So even though four 5/8in. bands work very well, I still want 21mm grunt
