1+4 means a model where the big toe is separated from the other toes. The socks are suitable for use with 1 + 4 shoes as well as regular shoes. Slip toe reduces sweating of the feet and the movement of the sock on the foot. Bamboo socks are not only very soft and pleasant to the foot, but also inherently antibacterial. You are more likely to have fresh feet all day long! Size options S/M and L/XL.