Originally Posted by Kevin K

Black has the same shore rating as Magenta 35 shore....but it works out to be right between a Purple and a Magenta as far as grip goes. Its not from the same family of foam so the way it heats up and builds traction is not the same as the other two. IMO the blacks feel like a magenta but dont get too sticky into the run like purples can. They work really well when the grip is higher but not so well when the grip is lower.