Track no wax

Classical (Diagonal) Track only - no-wax (narrow, lightweight)

In 'the good-old-days', people waxed their skis so that with sufficient weight, they would stick to the snow and with less weight, they would glide. Kick-'n-Glide. And they still do this, but it's really hard to wax for temperatures right around freezing and/or icy conditions. Which is what we have a lot of here in the Pacific Northwest. (And that they have a lot of at many of the sites where international ski races are held.)

Hence the development of fast, skinny, lightweight skis that don't need waxing. I never tried these until I moved to the PNW. After spending a winter here, I went out and bought a pair. There are two directions to go:

'Fishscale' - a pattern carved into the base of the ski. Depending on how 'aggressive' the pattern is, they might have stronger kick or better glide - but not both in the same ski. This is what I use and they work pretty well.

'Skins' - a relatively new addition to the choices (although they were tried 40 years ago). Strips of mohair are embedded in the ski bottoms. The 'hairs' slide one way but stick backwards, giving you kick. They have better glide than the fishscale (and are quieter). I would be concerned about how well they wear over time. Some are replaceable if you are ready to deal with that. I believe that some are being used in international racing during problematic waxing conditions. More on 'skins' courtesy of Cross-country Skiing Planet

They are sometimes called 'zeroes' for skis that are used at 0 degrees (Celsius) (which is when waxing is particularly difficult)

The three numbers: the same as waxable track skis. 43.43.42 for example. No sidecut, made to be used in tracks.

* About the Ski-to-Sea race: All the fast skiers skate ski the race. But it's pretty hilly! For some of us of 'a certain age', a disadvantage of skate skiing is that we can't keep it up and can't power up the hills like Kikkan can. The advantage of diagonal skiing for me is that I can adjust my pace to how much energy I have and can therefore get to the end of a race course. I've done the Ski-to-Sea a couple of times using my fishscale track skis (43.43.42) and have been satisfied with my results. (Unfortunately, they do not set the classic tracks on the course.) I would use 'skins' instead if I owned them. For a little more, see this page.