Ugg boots are known in Australia and New Zealand as a unisex style of sheepskin boot made of twin-faced sheepskin with fleece on the inside and with a tanned outer surface, often with a synthetic sole. The boots originated in those countries, initially as utilitarian footwear worn for warmth and comfort and later adopted by surfers there during the 1960s. In the 1970s, the boots were introduced to the surf culture of the United Kingdom and the United States by local surfers returning from surfing competitions in Australia. Ugg boots emerged as a fashion trend in the United States in the late 1990s and as a world-wide trend in the mid-2000s, yet in Australia they are worn predominantly as slippers and associated with "daggy" fashion sense, and "bogan" culture. There has been a dispute between some manufacturers of ugg boots, as to whether "ugg" is a protected trademark, or a generic term and thus ineligible for trademark protection. In Australia and New Zealand, where the term is considered generic, more than 70 registered trademarks include the term UGG in various logos and designs. By contrast, UGG is a well-known brand of the California-based Deckers Outdoor Corporation, with registered trademarks in over 130 countries worldwide including the U.S., United Kingdom, Canada, all European Unionmembers, and China. Noteworthy manufacturers include Deckers, which reportedly has 95% of the worldwide market share; Luda Productions of Australia, which has roughly 75% of the market share in Australia; EMU Australia; Blue Mountains Ugg Boots; Mortels Sheepskin Factory; Bearpaw; Uggs-N-Rugs and Westhaven Industries, a government owned institution that employs disabled workers.