Consider the Ironman Surge Pro the ideal sock for trail running. It is thin to enhance feel for the surface and to minmise water absobtion, as well as foot hugging and breathable.
Foot hugging fit • Lightweight design • Breathable mesh instep • Seamless toe closure
medium womens US 6 - 10 ; mens US 5 - 9.5
large womens US 10 - 13 ; mens US 9 - 12