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Forty Below K2 Superlight™ Overboots

The Forty Below® K2 Superlight™ overboot is a great choice for extreme cold climbs. A favorite insulated boot cover that has been used for many years on Denali, Himalayas, and Polar expeditions. The unique design allows it to be used with a wide range of “step-in”, “new-matic”, and “strap-on” style crampon bindings, plus “wire toe bail style” ski mountaineering bindings.
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).

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The Forty Below® K2 Superlight™ overboot is a great choice for extreme cold climbs. A favorite insulated boot cover that has been used for many years on Denali, Himalayas, and Polar expeditions. The unique design allows it to be used…

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Specs Sizing
  • Fits over double shelled mountaineering boots.
  • Also fits over single mountain 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 chart below shows the overboot size as it compares to the sole length of the actual boot that it will cover:

Size Boot Sole Length
XS 10-11"
Small 11-11.5"
Medium 11.5-12.25"
Large 12.25-13"
XL 12.75-13.5"
XXL 13.5-14.5"


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Reviews 54321 5/5 stars based on 2 reviews.


Fast delivery. Haven't used it yet.

The delivery was fast. I can't review the product yet, cause I send it to a friend's address in the US and she is going to bring them to me just in october, as I'm going to use them in december in Mountain Aconcagua. If you are reading this by then, you can email me for information wink vanessa88.vmb@gmail.com

Use Situation: I will use it over my trekking boots to summit Mt. Aconcagua next december.

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Used these overboots recently on Denali. Worked very well. Went over my Scarpa's easily even at -10F. Also used them with my plastic boot liners as around camp boots. Thanks for including the repair tape. I needed it after using them with crampons only a couple of hours. Only "drawback" if you can call it that, they smelled like a cow barn right out of the package. Why is that??

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I purchased the Forty Below K2 Superlight Overboot for climbing during cold and deep snow conditions that exist in the Sawtooth National Recreation Area located in Stanley, Idaho. I would highly recommend you call customer support before ordering these overboots, esspecially if you have never worn overboots before, as they will fit differently for different types of boots. They work like a charm, no complaints here. Definately worth the $$$.

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