plastic i belive
+karma but im wondering y my boots were cramped in the shop but got so soft in the foot. i have a widefoot and was rockin crossmax 10s, was it that i went with a too narrow brand?
As an out of practice bootfitter (that will change in the next month or two) I will vouch for this. Plastic won't pack out. Liners will, regardless of what kind of liner you have.