Waiting for my new Fusion to arrive. Trying to figure out undies. I had Fourth Element Xerotherm and Arctic I loved, but they didn't fit me properly, so I sold them some months back. Kept the Arctic socks. 
I have an AL MK2 (one layer fleece onesie). Thing actually fits me, so I'm trying to figure out layers for it. But it's not very warm on it's own. I'm thinking the REI mid-weight merino wool layers with a silk layer underneath because wool makes me itch. I've used silk undies in the winter for years.
I didn't get the Thermal Fusion because everyone says it's super warm. I get hot easy and that's not a good thing.
I have an AL MK2 (one layer fleece onesie). Thing actually fits me, so I'm trying to figure out layers for it. But it's not very warm on it's own. I'm thinking the REI mid-weight merino wool layers with a silk layer underneath because wool makes me itch. I've used silk undies in the winter for years.
I didn't get the Thermal Fusion because everyone says it's super warm. I get hot easy and that's not a good thing.
