Mack Hollins is securing his northern credentials as a member of the Buffalo Bills with a new cold exposure challenge.

Buffalo Bills receiver Mack Hollins is walking in a winter wonderland, barefoot, ahead of "Sunday Night Football" against the San Francisco 49ers.

“Frostbite is a freezing injury to the body’s tissues caused by prolonged exposure to cold,” Johns Hopkins Medicine says. “It can cause lifelong (permanent) damage to the body. The most common places affected by frostbite are the fingers, toes, cheeks, chin, ears, and nose.”