Spinning Shetland Wool
The Shetland sheep produce a variety of wool types. This is some I am spinning right now, the turquoise is from a Shetland with a single coat and the black with white is a Shetland with a double coat.
The double coated fleece has two layers, an outer layer that is a bit thicker, the white in this case and the inner layer that is a shorter, finer fiber, the black. The outer layer helps to keep the under layer clean and dry.
This yarn will be used to make some socks because the outer layer of fiber on the double coated fleece provides some extra resistance to wear.