The headband style or the cap? I've got both. The headband has the same material inside and out (acrylic; I got the blue polkadots) but has a ~6" strip of black material sewn into the front as well that's maybe a little more absorbent than the acrylic. I haven't had a problem with it slipping but it's pretty snug. The cap is knit material on the outside and on the inside there are just thin nylonish pockets that the hard plastic panels fit into; the foam (neoprene??) lining of the hard plastic is in direct contact with my head. That one fits pretty snugly as well; I just don't like it as much for some reason.