The Skully is ideal for layering under a helmet. 3-D -form fitting three-panel construction. Flat lock stitching provides comfort and durability. Shaped bottom provides full coverage and prevents excessive gathering. Dri-release wool gives you the best of both worlds--the ease of care of a synthetic and the aesthetics of a natural fiber. Machine washable and dryable. Wool absorbs and evaporates moisture so it never feels clammy or sticky against the skin. Dri-release wool has also proven to have greater thermal properties than other wool blends.