NSA Heavy Fiberglass Extreme Heat Lined MittenNSA Heavy Fiberglass Extreme Heat Lined Mitten Some jobs demand the absolute maximum in hand protection. The NSA Heavy Fiberglass Extreme Heat Lined Mitten is engineered for workers who operate in the most punishing heat environments think molten metal handling, glass manufacturing, and heavy foundry work where ordinary mittens simply won't cut it. Built with a heavy duty fiberglass outer shell and an extreme heat thermal lining, these mittens are