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  • Durable yet soft polyester/spandex blend fabric wicks moisture and dries quickly
  • Mineral-based LAVA™ finish keeps fabric odor-free
  • Flatseam construction, low-profile waistband and crotch gusset keep youngsters comfortable as they move
  • UPF 50 sun protection
  • Fly opening
  • Fitted


View all REI Co-op Kids' Long Underwear Bottoms

REI membership


Best Use Multisport
Fabric Merino Wool
Sun-Protective Fabric Yes
UPF Rating 50
Moisture Wicking Yes
Quick Drying Yes
Underwear Weight Midweight
Gender Girls', Boys'

Size chart

Rated 2 out of 5 by from Itchy These will get the job done. They're warm, but they're incredibly rough and itchy like the wool you were afraid of as a kid. They are a bit baggy around the waist and the elastic is quite stiff.
Date published: 2017-02-09
  • y_2017, m_5, d_19, h_6
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