As you probably know, many species of domestic farm animals are dying out. We support "Species Protection" because we feel it's important to keep those gene pools as complete and pure as possible. Plus these species are typically hardier and more self-sufficient than commercial breeds, which in the long run are better for the environment. Buying these slippers provides incentive for herders to keep these species thriving. These booties are felted with un-dyed wool, from the protected species of Gotland Sheep, one of the oldest sheep breeds worldwide. We talked our Austrian maker of our fabulous, rare-species, wool felt slippers to make them for both indor and outdoor use. A great idea prompted by you, our customers, who hate to take off their toasty warm slippers when going outside. To that end, we offer these fabulous Gotland Sheep felted wool slippers, anatomically shaped with a sustainable, lightweight cork inlaid rubber sole. You will love these so much you'll never want to take 'em off. Come in European sizes 36-46. See U.S. conversion chart below.