Smartwool Classic Thermal Merino Base Layer Crew – Kids' color-green The O FIT Insole adds

The O FIT Insole adds support where most low hikers cut corners

Engineered mesh upper with reinforced overlays balances breathability and durability through miles of rough use

while Vibram Megagrip keeps you planted on wet rocks

Raglan sleeves and side-panel construction give babies and toddlers a comfortable fit that layers easily over base layers

Smartwool Classic Thermal Merino Base Layer Crew – Kids' color-green The O FIT Insole addsBuilt for active kids who won't slow down when the temperature drops, the Classic Thermal Merino Base Layer Crew is our top pick for cold weather layering. Merino wool naturally regulates body temperature and resists odor, so they stay comfortable from first chair to last run. Flatlock seams cut down on chafing during all day movement. Merino wool construction provides natural warmth without bulk regulates temperature as activity levels change