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Oct 9, 2026
Lives in my rotation
The fir green is even prettier in daylight. Fits close without clinging, and it came out of a cold, gentle wash looking new.
Seasonal price
Men's Thermal Underwear Long Heated Base Layer Pants USB Rechargeable Slim Fit
4.8 · Read reviews
$109.99
$189.99
Save 42%
Free US shipping · Taxes calculated at checkout
Secure, encrypted checkout · Visa, Mastercard, Amex, Apple Pay, Google Pay
Free US shippingShips in 1–2 business days, arrives in 3–4
90-day returnsPrintable label, refund to your card
Ships from North AmericaNo customs, no import fees
Designed in PortlandMade to last for many seasons
Questions about fit or fabric? Email contact@willamettefir.com. We reply within a few hours.
Description
Heated Thermal Underwear Pants with USB Rechargeable Technology
Mens thermal underwear pants engineered for serious cold-weather performance. The slim fit design hugs your body without restricting movement, while the soft synthetic fabric and flatlock seams deliver comfort that lasts through long days outdoors. Perfect for winter sports, cold-weather commuting, outdoor work, and any activity where staying warm matters.
One of our most-loved pieces this season for anyone serious about layering through winter.
Selling fast in all sizes. Ordered today, dispatched within 24-48 hours.
Why You'll Love These Heated Pants
- Slim fit design: Sits close to your body without bulk, letting you layer comfortably under regular clothing or wear as standalone heated base layer pants.
- Soft, stretchy synthetic fabric: Moves with you through any activity while maintaining durability and quick-dry performance.
- Versatile warmth for every season: Whether you're tackling winter sports, heading out for outdoor work, commuting through freezing temperatures, or enjoying cold-weather activities, these rechargeable heated pants adapt to your needs.
- Multiple heating zones with three temperature levels: Customise your warmth with integrated heating elements controlled via an easy-access square power button—find your perfect comfort setting instantly.
- Flatlock seams and secure battery pocket: Reinforced stitching eliminates chafing, while the zippered battery pocket keeps your power bank secure and accessible.
Material & Care
- Fabric: Synthetic blend with integrated heating elements
- Construction: Flatlock seams for reduced chafing and durability
- Features: Elastic waistband, full-length legs, zippered battery pocket for power bank storage
- Power: USB rechargeable with three adjustable temperature settings
- Care: Follow manufacturer washing instructions to preserve heating elements and fabric integrity
Available in sizes XXS through 2XL to ensure a proper fit for every body type. We recommend checking the size chart before ordering to find your ideal fit. These heated thermal underwear pants are designed to fit snugly as a base layer while allowing freedom of movement for active pursuits.
Don't let winter slow you down. Grab your heated base layer pants while stock lasts—this season's demand for quality rechargeable heated apparel has been exceptional. Order today and receive your electric heated pants within 48 hours, backed by our money-back guarantee if you're not completely satisfied.
Fit & sizing
True to US sizing. Not sure? Use Find my size above for a personal recommendation, or check the size chart. Coats are cut with room for a sweater underneath.
Material & care
Chosen for warmth, softness and a long life. Air wool and knitwear between wears, wash cold on a gentle cycle or by hand and dry flat. Dry clean coats and tailoring.
Shipping & delivery
Free standard shipping on every US order. We process orders within 1–2 business days and ship from our North American warehouse. Delivery takes 3–4 business days. You'll get a tracking link by email as soon as your order ships.
Returns & exchanges
You have 90 days from delivery to return unworn items with tags attached. Email us and we'll send a return label to print. Return shipping is paid by the customer, except when an item arrives damaged, faulty or not as ordered. Refunds go back to your original payment method.
About Willamette & Fir
Designed in Portland, Oregon, for the long, wet, beautiful seasons of the Pacific Northwest. Quiet, well-made pieces meant to be worn for years.
Customer reviews
What our customers say
4.8
from verified buyers
Oct 8, 2026
The coat I was looking for
Warm enough for a wet Portland morning without feeling heavy. The wool is soft and dense and the shoulders sit right. The size finder said S and it was spot on.
Oct 7, 2026
Sharp and actually warm
Wore it all week in the rain over a sweater. The collar stands up properly and the buttons feel solid. Sleeves were a touch long for me, an easy fix at my tailor.
Oct 6, 2026
Softer than I expected
No itch at all, and no pilling after a month of weekend wear. The cream is warm, not stark white.
Oct 5, 2026
Broke in fast
Two days of walking and they were comfortable. I went half a size up for thick socks like the size finder suggested. Perfect.
Oct 4, 2026
Great on the trail and in town
Shed a full afternoon of drizzle in the Gorge. Pockets are deep enough for a phone and gloves.
Watch
Oct 3, 2026
My favorite coat this fall
Cozy enough for early dog walks and still polished for coffee after. I'm 5 ft 4 and the XS was right.
Oct 2, 2026
Elegant and easy
Wore it to a wedding with boots and a blazer. The knit drapes nicely and doesn't cling at the hips.
Oct 1, 2026
Lovely packaging, fast delivery
Ordered on Monday, arrived Thursday. Everything wrapped in tissue, no plastic mess. The scarf is generous and very soft.
Sep 29, 2026
Classic and well made
The navy is rich and the lining is smooth. I exchanged for a size up and the team answered my email the same morning.
Sep 27, 2026
Exactly as pictured
The oat color is soft and warm, just like the photos. Real horn buttons and a cable that keeps its shape. Shipped the next day.
Sep 25, 2026
Warm without the bulk
Light enough to wear all day, warm enough for frosty mornings on the lake. Got compliments twice on the first trip.
Complete the look
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Styled in the Northwest
How to wear it
Ideas from our Fall/Winter 2026 lookbook.
Help
Questions before you buy
Which payment methods do you accept?
Visa, Mastercard, American Express, Apple Pay and Google Pay. Every payment runs through Shopify's encrypted, PCI-compliant checkout, so we never see or store your card details.
When is my card charged?
Your card is charged when you place your order. If an item turns out to be unavailable, we refund it to your card right away and let you know by email.
Can I change or cancel my order?
Yes, as long as it hasn't shipped. Orders leave our warehouse within 1–2 business days, so email contact@willamettefir.com as soon as possible with your order number.
Do I need an account to order?
No. You can check out as a guest. With an account you can see your order history and track deliveries in one place.
How much does shipping cost?
Standard shipping is free on every order within the United States.
How long will delivery take?
We process orders within 1–2 business days. Delivery then takes 3–4 business days, so most orders arrive within 4–6 business days.
Where do you ship from?
From our North American warehouse. There are no customs fees or import duties for US orders.
How do I track my order?
You'll receive an email with a tracking link as soon as your order ships. Tracking can take up to 24 hours to show the first scan.
What is your return policy?
You have 90 days from delivery to return unworn items with the original tags attached.
How do I start a return?
Email contact@willamettefir.com with your order number and we'll send you a return label to print. Return shipping is paid by the customer and we confirm the cost before you send anything. If an item arrives damaged, faulty or not as ordered, the return is free.
When will I get my refund?
As soon as your return is checked in at our warehouse, we refund your original payment method and email you a confirmation. Your bank may need a few more business days to show it.
Can I exchange for another size or color?
Yes. Tell us which size or color you'd like when you email us and we'll set it aside while your return is on its way.
How do your sizes run?
Our clothing follows standard US sizing (XS–XXL). Every product page has a size chart and the “Find my size” tool.
How does “Find my size” work?
Enter your height and weight, then answer two or three quick questions about your build and how you like things to fit. It adjusts for the type of garment, for example more room in coats if you layer, and recommends a size you can add to your bag directly.
What if I'm between sizes?
For coats and jackets you plan to wear over knits, take the larger size. For knitwear and tailored pieces, take your usual size for a cleaner fit.
Can someone help me choose a size?
Of course. Email contact@willamettefir.com with your height, weight and the item you're considering. Our fit team usually replies within a few hours.
How do I care for wool and cashmere?
Air knitwear between wears and wash only when needed: cold, gentle cycle or by hand with wool detergent, then dry flat. Coats are best dry cleaned. Store knits folded, not on hangers.
Where are your clothes designed?
Every collection is designed in Portland, Oregon, and shipped to you from our North American warehouse.
Are the colors in the photos accurate?
We photograph in natural daylight to keep colors true. Screens differ slightly, so if a shade isn't what you expected, you can return or exchange it within 90 days.
How long does the Fall/Winter 2026 pricing last?
The seasonal pricing of up to 40% off applies to the new collection for a limited time and while sizes last.
Still have a question? Email contact@willamettefir.com and a real person will reply within a few hours.