Ugg released its highly anticipated Ugg Crochet Boots in late 2007. As with all Ugg boots, the crochet version is lined with sheepskin and has a patented Poron memory foam sole. The knit exterior is flexible, allowing for slouched or tall wear. Crochet Uggs quickly became one of the hottest selling footwear items during the 2007-2008 winter season. In Spring 2008, the Ugg Crochet Boots were still sold out at many retailers.