I just read in the Excal forum that the excel string is made of excellerant string which is made of........... dacron! I did not know that excellerant is dacron. Dacron is my fav material for xbows and will continue to be as well. The only problem is that my vixen came with an Excel string and it does not look like my dacron string at all. My dacron endless loop string is all black and the excel string is brown and green. I will have to get to the bottom of this!