CB string
"Pick up several when you purchase the 50# crossbow kit. At this price it is well worth it. Throw 'em in your pack for "just in case". They do wear out after a while and to be without replacement can put a quick end to a fun day. I also suggest getting lube oil/string wax at purchase. Again, if it is in your gear kit and handy, you can take time out to repair and get back to it, rather than calling it a day due to malfunction."