BCY's new B55 is a durable, 100% high-performance polyester string material. (Polyester is the kind of material the old slower "Dacron" was made from.) This new low-stretch polyester is faster than ever, but still safe to use on any bow, new or old. This is the perfect string to get better performance than standard Dacron without any chance of harming the bow. Each ¼# spool holds approximately 1,100 feet.