Lenz 5.0 is a technical sock with built-in heating elements that can be paired with the Lenz battery pack. The socks are ergonomically designed and snug around the foot without any folds. The sock is breathable and is reinforced around the foot's most sensitive parts. The sock is also reinforced on the shin to provide increased comfort for Alpine skiers. Slim fit. The package includes socks (battery pack can be purchased separately).