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Lightweight Base Layers

(94 products)
Products (94)
Sort: Best Match
    SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Women's
    $49.83 - $74.99
    Save 25% - 50%
    compared to  $100.00
    100 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    Top Rated
    SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Men's
    $74.99
    Save 25%
    compared to  $100.00
    106 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    SmartwoolClassic All-Season Merino Base Layer Bottoms - Women's
    $49.83 - $74.99
    Save 25% - 50%
    compared to  $100.00
    25 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    Top Rated
    REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Men's
    $67.39
    Save 25%
    compared to  $89.95
    137 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's
    $59.89
    Save 25%
    compared to  $79.95
    228 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Text reads: ‘Anniversary Sale 2026. 25% off’ over a collage of Smartwool long-sleeve shirts and colorful socks.

    Save 25% on all Smartwool clothing

  • Sale Ends May 25
    REI Co-opMerino 185 Long-Sleeve Base Layer Top - Women's
    $59.89
    Save 25%
    compared to  $79.95
    246 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Women's
    $33.69
    Save 25%
    compared to  $44.95
    38 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Men's
    $33.69
    Save 25%
    compared to  $44.95
    41 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big, Tall
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Base Layer Bottoms - Men's
    $33.69
    Save 25%
    compared to  $44.95
    28 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big, Tall
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Half-Zip Base Layer Top - Women's
    $37.39
    Save 25%
    compared to  $49.95
    17 reviews with an average rating of 4.8 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Women's
    $59.89
    Save 25%
    compared to  $79.95
    122 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Men's
    $59.89
    Save 25%
    compared to  $79.95
    169 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Base Layer Tights - Women's
    $33.69
    Save 25%
    compared to  $44.95
    11 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus, Petite
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino Base Layer Bottoms - Men's
    $74.99
    Save 25%
    compared to  $100.00
    30 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino T-Shirt - Men's
    $71.19
    Save 25%
    compared to  $95.00
    111 reviews with an average rating of 4.0 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    REI Co-opLightweight Half-Zip Base Layer Top - Men's
    $37.39
    Save 25%
    compared to  $49.95
    24 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Top - Women's
    $52.39
    Save 25%
    compared to  $69.95
    67 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Crew Base Layer Top - Women's
    $26.19
    Save 25%
    compared to  $34.95
    30 reviews with an average rating of 4.8 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    Icebreaker125 Cool-Lite Merino Blend Sphere III Scoop T-Shirt - Women's
    $67.49
    Save 25%
    compared to  $90.00
    28 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino T-Shirt - Women's
    $71.19
    Save 25%
    compared to  $95.00
    110 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    Top Rated
    REI Co-opLightweight Crew Base Layer Top - Men's
    $26.19
    Save 25%
    compared to  $34.95
    32 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big, Tall
  • Sale Ends Today
    Free CountryForce Grid Fleece Base Layer Bottoms - Women's
    $19.73
    Save 64%
    compared to  $55.00
    11 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    REI OUTLET
  • Sale Ends May 25
    SmartwoolIntraknit Thermal Merino Base Layer Bottoms - Men's
    $112.49
    Save 25%
    compared to  $150.00
    33 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Women's
    $67.39
    Save 25%
    compared to  $89.95
    112 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    Top Rated
    SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Women's
    $69.73
    Save 26%
    compared to  $95.00
    6 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    REI OUTLET
    Arc'teryxRho Base Layer Bottoms - Women's
    $59.83 - $100.00
    38 reviews with an average rating of 4.0 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Limited time only! The R E I Co-op Mastercard.

    Get $130 in value

    When approved for the REI Co-op Mastercard by May 25, you’ll get $30 in card rewards. Plus, you can earn a $100 REI gift card after your first non-REI purchase within 60 days from account opening. Terms apply.

    Kari TraaKlara High-Waisted Base Layer Pants - Women's
    $62.73
    Save 30%
    compared to  $90.00
    14 reviews with an average rating of 3.9 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    REI OUTLET
    tasc PerformanceElevation Merino T-Shirt - Men's
    $46.73 - $54.73
    Save 30% - 40%
    compared to  $79.00
    55 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Big, Regular
    REI OUTLET
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Top - Men's
    $52.39
    Save 25%
    compared to  $69.95
    60 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    HalfdaysSophia Base Layer Leggings - Women's
    $29.83 - $71.19
    Save 25% - 68%
    compared to  $95.00
    123 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
Sort: Best Match

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