North Face Hyvent Gaiters. Product Name: Hyvent Gaiters Purpose: Protection from rain and mud for mountaineering boots Product Number: NN21202 Color: Blue Outer Material: Nylon Inner Material: Polyester Function: Waterproof Season: All Season Size: L Used once on a Mount Fuji climb and then stored at home. Therefore, there are areas with age-related deterioration and white stains. Please purchase only if you understand that this is a personal inspection and has been stored at home for a long time. Please refrain from purchasing if you are looking for a pristine item or are overly concerned about condition.