Winners choice standard strings are made of 8125. However you can request other materials such as 452, D-75 thin, ultracam, and TS1.

All of their strings are made with fibers that have been prestreched before the string is made and once installed and shot a minimal number of times they will not ever move on you again. They also serve their strings in such a way that they guarantee no serving separation for one year. Even on the very sharply turned corners on modules.

I have used WC strings and others and I still think that the WC strings and cables are a better string. They are a little pricey but once your bow is tuned it stays tuned. The peace of mind knowing that nothing is ever going to move on you is worth the extra money IMHO.