Are you asking about a string for self bows, vintage glass bow or new glass bow? If they are older vintage glass bows and the tips are not designed for fast flight strings and you'll want to stay with B-50. There isn't enough difference or improvement in B-55 to make it worth considering. If you need a string for one of the newer glass bows designed for fast flight materials or even a self bow or laminated wood bow, then there are numerous fast flight materials that will do a good job.......some considerably more expensive than others.