MacEntyre has used these mukluks as low as -20*F, using one pair of wool socks and mil-surplus wool felt boot liners, with excellent results.These mukluks work very well with snowshoes. Unlike mukluks that have a heavy sole and more structure, they will not tear up traditional snowshoes.
An athlete generates as much as 8 oz of moisture while wearing mukluks. Feet are nonetheless warm because the mukluks are breathable, so moisture passes through. Each night, the mukluks should be dried by removing the liners and inserts, and hanging them and the socks in a heated area. Traditional mukluks dry much faster than other footwear, because they are made with 100% breathable materials, and can be taken apart. For this reason, I do not recommend using mink oil or any other waterproofing treatment on mukluks. If you wear them only on snow and ice, the leather soles will last a long time.
Wool inserts are optional, but extremely effective, especially when temps are warm enough for water to melt (above 20*F). If you want to use them, it is best that I include them with the liners when I make the mukluks, because they do take up a little bit of room. The only other thing the athletes will need is 100% wool socks.