I have put them on two Hills (63# @ 29" Wesley Special, Big 5 53# @ 28"). I used 10 strands. I like them, but I also think I need string silencers when using them on Hills. When using B-50 I go without. It does seem that I can bump up a bit in spine, but not too much. I guess on the Hill styles, I would rather stick to B-50, just personal preference. I found I like using them on all of my other bows, and it seems to make them quieter (I know, it contradicts my earlier statement).