i used a 16 strand b-50 flemish twist string for the 2 piece bow i built. it came in at 49#@28" draw. plenty strong for that bow. it will last several yrs before it needs to be replaced. a b-50 string built to suit a certain poundage bow will work for ff bows the same cannot be said for high performance strings on a bow built as a string follow bow. even some glass backed bows will not except a high performance string.my self, i would never ,ever use a high performance string on an unbacked selfbow. do your research , even some glass backed bows,1 or multi piece bows with sheep horn reinforced tips will not except high performance strings.granted its got to do with the lams in the riser but , there are stresses on a selfbow that cannot handle the low stretch of a ff string. all bows no matter th configuration of their construction, have to work together.all components have to be a marraige made in in heaven, and have to work together, to function as a unit archer included. rv