COOLMAX fabric which is the best of both worlds; unsurpassed moisture management and LYCRA sport stability. Save our Soles specific knitting machines place the COOLMAX fabric on the inside of the socks where it controls moisture from the foot; while the 3-ply nylon is used on the outside of the sock for strength and durability. The core-spun yarn is the most efficient way of knitting LYCRA fabric into the foot of the sock and still allow both the COOLMAX fabric and nylon to be sandwiched together. The cool designs are just a disguise; it's a unique construction of the best materials and is unmatched anywhere.