The size L out of the box is too small for my 29.5 Full Tilt boots. The directions say soak in warm water, and that did help, but it was a hassle getting them on there. They’ve gotten easier, and I’m sure I don’t want them loose and falling off, but it’s still pretty tough to apply them.
I have used these for years. The large is a bit tight but hopefully they will stretch out as I leave them on my boot when storing them. They also fold up nicely when you are ready to ski and you can stick them in your ski jacket.
I have large boots (325mm) so I put the track in boiling water before putting them on my boots. Now they fit. They last just about as long as I own the boot as well.