

❄️ Gear up in Carhartt Base Force® — where warmth meets unstoppable performance!
The Carhartt Men's MBL121 Base Force® Heavyweight Base Layer Pants combine advanced Force technology with a durable synthetic-merino wool blend to deliver superior moisture-wicking, odor resistance, and temperature regulation. Designed with flatlock seams and a contoured fit, these base layers provide long-lasting comfort and durability for cold-weather work or outdoor activities.
























| ASIN | B0BMT1H3SY |
| Best Sellers Rank | #39,778 in Clothing, Shoes & Jewelry ( See Top 100 in Clothing, Shoes & Jewelry ) #46 in Men's Thermal Underwear Bottoms |
| Customer Reviews | 4.5 4.5 out of 5 stars (1,751) |
| Date First Available | August 10, 2021 |
| Department | mens |
| Item model number | UM0121 |
| Manufacturer | Carhartt |
A**R
Last longer than Merino wool
I recently purchased the Carhartt Men's Force Midweight Synthetic-Wool Blend Base Layer lowers and upper, and I have to say, I’m really impressed with it! After wearing it for about a month, I’m very satisfied with both the quality and comfort. I tested these while hunting and while at work. The blend of synthetic and wool material provides a great balance of warmth and breathability, making it perfect for those cooler days. The fit is spot on, it's snug enough to keep me warm without feeling restrictive, and it holds up really well throughout the day. The fabric is soft against the skin and doesn’t itch like some other wool blends I’ve tried in the past. I also love how moisture-wicking it is. Whether I’m working hard outdoors or just running errands, it keeps me dry and comfortable. Carhartt's reputation for durability definitely holds up with this base layer; it feels built to last. I haven't noticed any pilling or wear even after a month of consistent use, which is a huge plus. I’m looking forward to seeing how it holds up over the long term, but so far, it's been an excellent purchase. Highly recommend it for anyone looking for a high-quality, comfortable base layer that can handle whatever you throw at it.
P**K
Works great!
I got this product because I am constantly outside for work in the winter. I have had it for 3 years and it still feels comfortable, doesn’t have any holes so it’s durable. It functions great in keeping me warm, but is breathable enough when moving around to not get too how. I have worn it under my putter coat when offshore fishing during the winter as well as kept me warm while up in the mountains material is great, durable, and thick enough to keep warm but thin enough to not overheat. Glad I spent the money on this and looks good too!
B**S
It's a gift
And it's a gift worth giving, as Carhartt makes a good product on everything. He wears Carhartt everything as it's his 'go to.' While there are less expensive long underwear for base layers, the fact that Carhartt has 19% wool in them is what sold me. There is nothing at all like wool to retain heat - no fancy "fabrics" of any sort - and that these are also washable/dryable is amazing. He will be happy I am sure.
A**N
Warm, fits well
I am 6ft and 210 lbs. I got a large and it fits well. I was concerned about length because ive owned so many base layers that shrink and the ankles are halfway up my calves, which i hate. Length in great. Tighter in the crotch and butt than others ive had, but it actually works well because it doesn't feel as bulky under jeans and makes movement easier
K**S
Husband loves them
My husband and I live in Maine and he is a carpenter so it’s important he stay warm working the long days of winter. These were a game changer for him!! They keep him warm , durable and super comfortable. Easy to wash / dry. Def recommend
S**O
Quality
Great quality!
D**K
Very impressed
5’10, 165lbs I ordered a small and medium due to fitting within the smedium size. I typically wear a medium in Carhartt products and decided to just try them both out to see which one fit better. The small fits well with only one tight spot around the waist band. It’s not enough to cause any issue while carrying a pack during hunting season. The medium also fit well just a little looser. If you properly layer you clothes these work great! If you plan to do activities that cause sweating or getting wet these still work well but there are better options. I typically wear the classic full polyester base layer when I know I’ll be moving a lot, out in the rain, or moving through bodies of water. Being 81/19 polyester/wool blend it’s dries way faster than straight wool. If you’re looking for a good thermal these will do the trick. Reading other comments I’d stress this is just a base layer that needs additional layers to stay properly warm (wearing them alone will not keep you warm).
N**I
Great underlayer
I bought the top and bottoms for my boyfriend for Christmas. He loves them. He usually wears a small and they fit as expected. He’s 5’10” and weighs around 155 lbs and wears a 30x32 in pants. He says the material is soft, comfortable, lightweight, and most importantly keeps him warm working outside in cold Iowa winter temps.
J**L
Cómodo , ideal para climas fríos
C**N
Super warm. Wash and wear well, so far! True to size and made well!
J**E
Living in Canada, be it for the cold, under my work pants, knee pads or even motorcycle pants, I wear base layers more than half the year! I'm very pleased by those, always looking for a better, still have not found my ideal, this one is promising, time will tell!
A**M
Good baselayer working construction in Toronto. Not going to keep you entirely warm but you should be wearing layers on really cold days and this acts as a perfect baselayer. Was really happy with mine so I asked for two more pairs for Christmas.
R**R
Although I thought they would be a little too light duty, they performed well during our last bought of could weather.
Trustpilot
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