its about 2cm thick. Its stiff foam, and is ace as a foot cleaner mat, and I use it to put over individual rocks/pointy bits that might cause you some pain but are not really worth matting.. As its stiff its also really good to put across uneven surfaces under a bouldering mat - a mini platform if you like. As a stand alone ankle saver..? No. It might stop your foot getting bruised - and evens out the surface but its no substitute for a mat..