Gear Reviews

Smartwool Merino 250 Base Layer One Piece

Best onsie from the Fall/Winter 2018 Gear Guide.

Brand: SmartWool

Model: Merino 250 Base Layer One Piece


Winter body suits are all about simplicity. A single piece of fabric means a closed system for better body heat retention—and you never have to deal with exposed skin due to shifting hems. “Layers just fit better when they’re all one piece,” notes a tester. “There’s never extra material bunching up under my hipbelt.” Another tester was used to battling midriff sweat, but the single, continuous fabric wicked and breathed better than overlapping layers. 


This merino onesie employs a double-interlock knit, which packs more yarns per   square inch for extra warmth— meaning it’s best on the colder end of the spectrum (-10°F to 25°F). Female testers liked the hip-zip drop seat. Ding: Some testers found the ankle cuffs too loose to stay put but too tight to hike up.


“I don’t usually wear baselayers with a hood, but the one on this suit is a great integrated neck-and-head cover in sunny conditions, without being too warm,” one tester says. 

Weight: 1 lb. 3 oz. 

Sizes: Men’s S-XXL, Women’s XS-XL

See more of the best Baselayers for Winter 2018

See the entire Winter Gear Guide