The Toko Structurite Nordic Kit includes a structuring tool and three interchangeable rollers, so you can prepare the running surface of your cross country skis to best suit the snow conditions. Each roller's color corresponds to the type of wax that compliments that roller's structure. For cold conditions and fine snow, lean toward blue wax and the blue roller's linear structure. For freezing temperatures and below, steer toward red wax and the red roller's fine, broken structure. And for warmer conditions and moist snow, yellow wax and the yellow roller's aggressive broken structure are your best bet.