We made this skull cap low-bulk with our plated Merino/polyester construction. Soft against the ears, you'll find it warm enough for crisp days yet able to regulate temperature as things warm up. Its low-key styling can go from beneath the helmet to lunch spot without a costume change. - Transfer Merino fabric combines wool and recycled polyester for sustainable technical performance. - Unique plated fabric construction places polyester next to skin and merino on the exterior for superior moisture transfer and thermal regulation. - Made using fine 18.5-micron Merino wool for superior comfort. Recycled Repreve XS Polyester technical fibers are made from recycled plastic water bottles. - Close-fitting design easily fits under helmets and looks good on its own. BioViz reflective elements for low-light visibility. - Wool Blend Performance certified by the Woolmark Company to ensure the highest quality product.