We recommend these boots for ski and dogsled expeditions to the North Pole, ski expeditions to the South Pole and Svalbard ski expeditions. They have a 75 mm toe that fits with our three pin bindings. They are rated to -90 F. These boots run small. Please order at least one full size larger than you normally wear, if in doubt order two sizes up. Half sizes should order at least one and a half sizes larger than normal.