The Fremen garment which allowed desert survival by cooling the wearer and by preventing water loss. These slick, gray bodysuits were the second skins of Fremen — and of all those with good sense who had occasion to venture into the Arrakeen desert. An unprotected human, without access to a staggeringly large water supply, could last no more than a day on the sands; one wearing a stillsuit of Fremen manufacture, however, could keep water loss under fifteen milliliters per day. The less efficient versions of the suits produced in village factories by the Arrakeen peons were greatly inferior and offered no such level of protection.