UGG Classic Cardy are a style of unisex sheepskin boots lined with wool on the inside and with a tanned outer surface. UGG Bailey Button often have a synthetic sole is not universal. The natural insulative properties of UGG Ultra Shortgives thermostatic properties to the boots, the thick fleecy fibers on the inner part of the boots allow air to circulate and keep the feet at body temperature. This means that UGG Ultimate Bind Bootscan be worn without socks even in relatively cold weather.