A favorite insulated boot cover, The Forty Below® K2 Superlight™ model has been used for many years on Denali, Himalayas, Polar expeditions, and cold wilderness uses  around the world.  Fits double shelled and single boots for mountaineering and expedition use. 

Update 1-29-24 Out of Stock due to supply chain disruptions.  The next batch is due May 2024.  Sorry for the delay!  Please email us if you would like to be notified when they are back in stock.  Thanks!

Please see below for more details.



Forty Below® K2 Superlight™ overboots   

              “I wouldn’t go to extreme altitude without them!” JIM WICKWIRE

UPDATE 1-29-24
The next batch of K2 Superlight model overboots should be ready in May 2024. Please email us if
you would like to be notified when they are back in stock.  Please include your boot/shoe details (brand, model, size, and sole length measurement). This will get you on the list for immediate notification as soon as they are ready to go! We are so sorry for the delay!!

Key Features:
Fits over double shelled mountaineering boots and over single mountaineering boots.
Stretchy and easy to put on in the cold.
Fit with a wide range of crampon styles.
Neoprene insulation around foot, breathable gaiter upper.
Easy to repair.

The Forty Below® K2 Superlight™ overboot is a great choice for extreme cold climbs. It is a favorite insulated boot cover that has been used for many years on Denali, Himalayas, Polar expeditions, and beyond. 

Patterned to fit both double shelled and single style mountaineering boots. In addition to being used with double shelled boots for high altitude and cold weather climbs, they can also be fitted to leather climbing boots to help extend their temperature use range.

The Forty Below® K2 Superlight™ uses a special nylon covered, 4.7 mm stretchy closed cell neoprene foam insulation, with 2 layers of heat reflecting Titanium. This insulation goes from about the top of your climbing boot, completely around and under the boot, with no gaps in the insulation. The insulation panels are glued together and also stitched on the inside and outside surface, with no sewn through seams. They fit trim to the boot, and are not bulky. Because of the stretchy insulation material they are easy to put on in the cold, and they roll up small in your pack.

The toe and heel area have small triangular shape panels made of a slightly thinner neoprene insulation that allows for many wire toe bails and flip lever heels to simply compress the insulation and rest on the toe and heel groove of the boot. The toe, heel, and lower side area of the overboots have a thin rubber paint applied to add abrasion resistance and help protect the stitching. A 2 inch wide heavy duty velcro front closure goes all the way down to the toes for easy adjustment of laces. The upper gaiter goes up to just below the knee, and is made of a non-coated, windproof and breathable Cordura nylon to help minimize frost build up. Elastic drawcord top closure, with a cordlock on top of the gaiter. A special smooth nylon crampon patch is glued and stitched to the instep side of the neoprene for added resistance to crampon pokes, etc.

One of the great features of Forty Below® overboots is that they are easy to repair! This is especially helpful, as crampons and rugged terrain are so hard on everything they come in contact with. Repairing is easily done by simply gluing the poke holes together, using glues such as those for repairing neoprene fishing waders or wetsuits, like AquaSeal from McNett, etc. For the fabric gaiter repairs, the iron-on style fabric patches work well and are really easy to put on, and can in many cases eliminate the need to sew patches on. For repairs on the mountain, use the Forty Below® Repair Patches, which are a special sticky and stretchy tape that work great for repairs during a trip (one is included with the overboot).

Crampon Compatibility:

These pictures below show the various types of crampon binding styles that can be used with the Forty Below® K2 Superlight™ overboots on the double boots and single boots:

Double Boots: For example: La Sportiva G2 SM, Scarpa Phantom 6000/8000, La Sportiva Spantic, Scarpa Inverno, Koflach Expe, and most others.  Crampon bindings shown below are: “Strap-toe/flip lever heel”, “Strap-on”, and “Step-in wire toe/flip lever heel” (which may not show depending on the screen width of your phone/tablet)

K2 Strap toe flip lever heel
Strap toe/flip lever heel.

K2 Superlight With Strap On Binding
Strap on binding.

K2 step in wire toe flip lever heel
Step in wire toe/flip lever heel.

Single Boots: For example: Scarpa Charmoz, Lowa Renegade, La Sportiva Nepal, and most other technical climbing models.
Please Note: Single boots will usually not fit with overboots and “wire toe bail” crampon bindings because of the lack of space on the boot toe groove for the combination of the bail and overboot fabric to properly fit, which is why they are not pictured below. Please contact us if you have any questions or would like to discuss this for your specific set-up.

K2 Strap toe flip lever heel
Strap toe/flip lever heel.

K2 Superlight With Strap On Binding
Strap on binding.


WARNING: The user must try on the crampons to each boot and overboot combination to confirm a proper fit!  Some crampons will not fit certain combinations due to the condition of the boot, crampon, or shape and size relative to the shape and size capabilities of the crampon.  The user must confirm proper fit prior to using. Please contact us if you have any questions or would like to discuss this for your specific set-up.

COMPARISON CHART for the K2 and Purple Haze:
Please click to read the PDF document comparing the Forty Below Purple Haze and Forty Below K2 Superlight overboots: Compare PH and K2 2014

Here is a picture of the K2 Superlight™ in the black color, on the website of International Mountain Guides, on the top of Mt. Vinson in Antarctica! Please visit their Vinson page and their website for lots of really cool places they can guide you to use our overboots at https://www.mountainguides.com/vinson.shtml   Thanks for recommending our gear! 

For more information about all of our different models of overboots, please go to the All About Overboots Section,  which is located on our home page.  There is an overview of the different models and the boots they go over, and additional information about overboots and insulated boot covers.

© 2021

Product Photo Gallery:

Put the cursor over the picture to see the heading. Click on the picture to enlarge it and to view the full description. An arrow on the edge of the picture will enable forward and back movement through the set of pictures.

This first gallery is of the Forty Below K2 Superlight overboots being used over double shelled mountaineering boots:

This gallery shows them in use with single mountaineering boots:


Forty Below® K2 Superlight™ overboots :

ORDERING: We will select the proper size for your boots
from the information you provide us in the ordering fill-in boxes above.

Built in the USA!  Handcrafted in the USA. We use materials from the USA and our friends from other Countries around the world.

SIZING: XS-XXXL To fit from ladies 4 to mens 16.  Fits over “single” or “double shelled” mountaineering boots

OVERBOOT SIZING: Forty Below® Overboots are made with stretchy insulation materials, and have a wide range of different sizes and shapes of boots that a particular overboot model/size can fit.  Because of this wide range, we ask that you provide some basic information about your boot and crampon, and then we will select the proper size with that information for you.

COLORS:  2 color choices:
All Black
Black gaiter with Red foot.

WEIGHT:  1lb 5 oz. (588g) per pair size Medium.

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