Features of the Pearl Izumi Men's Merino Wool Sock Transfer merino fabric combines wool and recycled polyester for sustainable Technical Performance 18.5-Micron fine merino wool Repreve recycled polyester created from recycled plastic water bottles Flat toe seam construction provides superior comfort over toes Anatomic arch compression for a Performance Fit Mesh ventilation over top of foot Fabric Details Merino Wool/Recycled Polyester