- AFTCO presents the Insulated Hydronaut, their leading waterproof outerwear system designed to endure extreme cold temperatures. Featuring a durable 2-layer 100% nylon shell with 30K waterproof rating, plus a 100% polyester lining, this system is reinforced with Cordura at the knees and rear for premium resilience. Equipped with a 140 gsm fill batting for additional insulation, the Insulated Hydronaut also offers wider shoulder straps for improved pressure distribution and superior comfort in the shoulders and back.