Outstanding as wearing socks of ultrathin cotton or synthetic fiber on the inside. It is warmer though it is considerably thinner than the urethane socks of the fishing gear shop. It is short and easy to use. There is a small hole of ventilation, but it is enough because it is in the boots.
I worked outdoors, so I bought it because it is very cold and feet warm. I thought it would be possible to waterproof the rain, but I do not know if there is a partial hole in the instep of the foot and it can be waterproofed.