Jack Hammer
Contributor
I have a few different merino base layers. I mostly use the Smartwool as I feel its warmer and better quality. Just expensive. I use the 250 gram base layers. I also have some generic forget the brand name stuff that was a lot more cost friendly but no where near as warm. For warmer weather I'll use the REI stuff. REI claims it is a 150gm layer, its thinner and less warm than the Smartwool 150gm layer I have. Over the merino base I use a Santi 200gm or 400gm, depending on temps.