Fully insulated with 5mm Neoprene. This provides the optimal warmth, comfort, and waterproofing that you expect from a Muck Boot. An Airmesh liner is added for maximum breathability. We've added Spandura to the neoprene for added protection against wear and abrasion. New light weight construction allows for a more athletic hunt. We've added an etc sockliner to help reduce friction and heat buildup in your foot. EVA midsole cushions with every step