My 03 Pro 38 and Pro 40 wheely each came with the O2 strings and cables. They are fine, virtually no stretch. I did replace the serving on my 38 when I changed the loop. the serving had seperated under the loop. This didn' t happen with the WC. All in all the strings are great and Bowtech made a good business move. this way you don' t feel oblgated to buy $100 WC strings and cables when you want to replace them.