XT and XS are coated using two different methods. Because of that, XT strings last longer than standard non-coated strings, and XS strings last longer than XT.
XT is made with a treated wrap wire, which results in an extended lifespan over similar non-treated strings, as well as a natural feel.
XS is coated using a film coating which generally lasts even longer— delivering maximum string life—and affords a smooth feel. Each string satisfies a particular need in the market. XT has replaced our successful EXP line as an excellent coated option, while XS utilizes our new, ultra-thin coating to bring a premium coated offering to players who want it.