Combining the luxurious quality, wicking, and naturally odourless qualities of merino wool with the superb insulation of PrimaLoft yarns, the Castelli Alpha 18 Socks are ideal for your coldest adventures and when going out on the bike feels like a necessity more than anything else. Nylon heels and toes introduce durability and arch support bands hold the socks in place. Key Features PrimaLoft/merino wool blend Arch support band Nylon heel and toe 18cm ankle height