That grey thing is a super thick yoga mat, heres the amazon link

http://www.amazon.com/gp/product/B004XFW5Y2/ref=oh_details_o04_s01_i01

the thing works great. 0 Slippage. I used to have to wear workout gloves during yoga and lay down towels because my hands and feet would slip. but not with this thing. I use the black yoga mat for when I do core synergistics because I dont want to tear this thing up with shoes