Lightweight Next-to-Skin Performance
The Primus K1 Long John baselayer provides a powerful foundation for the rest of your system. A carefully balanced blend of wool and synthetic fibers ensures long-lasting durability, simple wash cycles, and fast, efficient moisture transport. Flat seams allow bulk-free layering, and a specialized fly delivers support and fuss-free access (even with gloves).
Our wool combines with synthetic fibers to create the ideal performance fusion for moisture management: wicking up and lifting out sweat, protecting against odors and wash shrinkage, increasing durability, and ensuring next-to-skin comfort. Your system’s moisture transport starts here.
The Ballhalla™ fly keeps you comfortable all day long with anatomical support and minimal bulk, and the unique design ensures easy access even while wearing gloves.
Flat-seam construction ensures all-day comfort, delivering a smooth next-to-skin feel and reducing bulk when layering up.
K1 - PRIMUS
WHEN TO USE
Below 50° F as a next-to-skin baselayer.
PAIRS GREAT WITH
Active insulation and softshells.
BENEFIT OVER OTHER LAYERS
Highly breathable, fast-drying layer that can have any other layer worn over it.
Learn more about layering:VIEW SYSTEM BUILDER
Body Material2.7 oz. piqué 78% polyester/27% wool
Weight (Size L)7.1 oz.
Trade Agreements Act Compliant
Designed in Seattle. Imported.
I have worn these twice so far- once under a pair of prana lightweight pants and once under jeans. Both times the Primus kept me nice and warm. I was not hot or feeling over-dressed. The fit was good. Ordered a size L, I usually wear a 34 x 32 jean and these were just a touch big and long. Nothing to complain about, just insight into sizing. These were as comfortable, if not more, compared to my REI brand 100% wool long johns. These Primus pants didn't seem as delicate as the wool pants- but only time will tell. The thicker waist band is appreciated.
I was looking for something to warm me up on 34* mornings but not be too hot for the rest of the day. These work great! I’m 5’10 and 195 lbs, slightly dad bod and the mediums are a great fit. The only thing is the crotch is super long and somewhat baggy (make your jokes) which made the flap pretty sloppy and would open up on me. Otherwise, pretty good.
These base layers are exceptional, while staying active in temps below 40 degrees I was not cold at all
Just be aware they are very tight around calf’s and a little loose on waist for sizing
Love them plus the horizontal opening is a neat feature.
I like them a lot. They feel like they pull a bit around the lower legs when I sit down, but I’m very un-used to wearing base layers. Overall they’ve performed well so far!
Need Help? Contact us with any size or fit questions. 206-767-0307
Primus L1 Long John
Height 5' 8" - 6' 2"
Short: -2 Inches Inseam
Long: +2 Inches Inseam
Waist Preferred Pant Waist
Hip 7" Below Preferred Waist
Inseam Regular Crotch to floor
Standard True to Size | Active Layering
Expedition Oversized | Static Layering