2mm soles, but you know, they've got a layer of something or another inside the shoe, and I think just the having more of a structure makes them feel different than the sandals.
I'm considering ordering the moc3s, just because even though they are also 2mm, they are supposed to have more ground feel than the regular mocs. Also, funny but the suede mocs I have keep my feet almost too warm (and now I've used them down to 18degrees, albeit on short runs), so the ventilation might be nice until things get wet and slushy. My only concern is that like NickW, I have narrow ankles, so slip on shoes with no adjustments usually don't work well with my feet. I love the company though, and the suede mocs I have held up in everything, including rain, sleet, slushy snow this winter, and only show a bit of wear I think because I wore them for walking and everywhere aside from running.
It's just funny b/c last year when I was first transitioning the soft stars felt like nothing on my feet. Now they feel like big thick boots.
Anyhow, sandals alone are ok down to low-mid 30s dry, sandals w/ socks (bought a pair of super thin toe socks) down to mid 20s, then low 20s something more would be nice but not sure I need all that runamoc has to offer. Might want to save those for sledding and stuff, damp conditions, and single digit temps.