Here is the link for anyone interested
Underground Elite :: The Sling Shot :: Mark Bell's Sling Shot
If you need any help with sizing give me a call or email. The material is similar to a stiff knee wrap; being that it stretches a bit so sizing isnt super strict. the pic on the website shows where to measure around the arm so you cant really go wrong.
A PL friend got our 40reps on 100kg using it a couple of weeks ago just to see what he could do.
And yes around 10% is the general consensus from customers.
Cheers
Nick