If it is going to be particularly cold (winter camping say) I always carry a pair of these. I have a pair of Goosefeet Gear’s which I have found more than satisfactory for well over ten years. Mine are Size: Medium and weigh 2.2 0z the pair. They cost US$65 (July 2019) but you can sometimes pick them up on Massdrop.
Zpacks also make them. Theirs are a mere 1.8 oz (same price). I have owned and used many of their products over the years. All have been excellent – just that I have never had the need for two pairs of down socks.
Of course I use my own 12 gram Dyneema moccasins for night-time footwear over the socks in case I need to go outside my tent on wet grass. I have a pair of Goosefeet’s Over booties, but do prefer my own – as they are not so steamy! Another alternative are these ultralight galoshes at 29 grams each – but only a couple of bucks!
Another alternative is these insulated over-booties by Montane which at least have the advantage that you can walk around in them – not so good in the sleeping bag afterwards though. I also own a pair of them. They are a bit heavier at 165 grams the pair.
