This luxurious and warm sock is a blend of two natural yarns - fine merino wool and baby alpaca. The 19 micron Australian merino fleece wool is sourced from graziers in Southern NSW. The baby Alpaca is sourced from Peru and is soft, supple and smooth containing microscopic air pockets which are perfect for retaining feet warmth. This sock is not recommended for high abrasion use such as in work boots. A Health Sock® with no tight elastic top.