Mikeler says it is but RSI rates it with a stiffness of 205. It also doesn't seem to be that great for tension maintenance at 14.26. I am currently using the black Xcel 16g and really like it, but it is going to get expensive at €25 a stringjob and it lasting me only about 6 hours. OTOH I found PPA for €5 a pack online. The million dollar question is: If you had early signs of TE would you put PPA 16g in your racquet?