The Forty Below® Purple Haze™ overboot is the choice of climbers for Denali, the Himalayas and cold weather expeditions worldwide. It fits mountaineering boots as well as some low profile snowboard boots.

Please scroll down for more product details, specifications, and pictures in use.

SIZING for ordering:  Please provide your boot details in the fill-in sections below, and we will pick the proper size for you!

1st Color Choice *

2nd Color Choice *

Your Boot Brand and Model *

Boot Size *

Boot Sole Length *

Measure the bottom of your boot sole from heel to toe in inches or cm, with this information, we will pick proper size for you.

Boot Details

Anything else you think might be relevant to overboot fit and sizing

Crampon Brand and Model *

Crampon Binding Style *


The Forty Below® Purple Haze™ overboot is the choice of climbers for Denali, the Himalayas, and cold weather expeditions worldwide. 

The easy to put on, full length insulated overboot for mountaineering, the Forty Below® Purple Haze™ overboot is patterned to fit over double shelled and single mountaineering boots.  The Purple Haze™ model is a very unique overboot in that it can stretch to fit easily over a wide range of double shelled mountain boot models, and also the large volume “combi-boots” such as those from Millet, La Sportiva, etc. They also fit nicely over large volume single mountaineering boots such as the La Sportiva Nepal for example.  It is important to point out that they no longer will fit over most AT ski boots or snowboard boots, as those types of boots have changed in their shape, and are much larger in girth, so we now make the Forty Below® Fresh Tracks™ model to fit those style of boots better.

The Forty Below® Purple Haze™ overboot is easy to put on in the cold, and fits trim to the boots and leg area.  It fits with a wide range of crampons and binding styles. Please see the “Product Specs” Tab on this page for more details on the product and it’s uses.

Key Features

  • Full length insulated boot cover
  • Easy and fast to put on in the cold and at high altitude
  • Fits over double shelled mountaineering boots, and large volume single mountaineering boots
  • Completely stretchy to fit a wide range of boot models
  • Fit with a wide range of crampons styles
  • Easy to repair

Purple Haze™ vs. K2 Superlight™

Please read the PDF document comparing the Forty Below® Purple Haze™ and Forty Below® K2 Superlight™ overboots:

Comparison Purple Haze to K2 (2014)

Ed Viesturs on the Purple Haze™

Special thanks to Ed Viesturs and Whittaker Mountaineering/RMI for using our gear, producing this video, and letting us share it with you!

For more information about all of our different models of overboots, please go to the All About Overboots Section where you will find an overview of the different models, the boots they go over, and additional information about overboots and insulated boot covers.

Crampon Compatibility

Double Shelled Boots:
The Purple Haze can fit with Double Boots with these 3 types of crampon bindings:

Single Boots:
The Purple Haze can fit with Single Boots with these 2 types of crampon bindings:

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 above. Please contact us if you have any questions or would like to discuss this for your specific set-up.

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.
PLEASE NOTE: CAUTION Using overboots with some snowshoe bindings advisory:
These overboots are strong, but will not resist the damage that can be caused by some snowshoe binding base plates. There are now several models of snowshoes with upward facing “spikes” and “raised ridges” made of strong plastics and sharp shapes, that will immediately cut into the fabric sole of the overboots, and is very difficult or impossible to repair. The general purpose of these snowshoe binding design is to grip the rubber sole of the boot that is in the binding. Many of these spikes and sharp shapes have shown to cut into the rubber of the sole of boots. It is advised to put a thick rubber layer on top of the snowshoe binding base to protect the overboot from damage. This type of damage to the overboots will not be covered under warranty. We do have some suggestions on different ways people have made accommodations to this, so please contact us to discuss.

Forty Below® Purple Haze™ Overboot 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.

The Forty Below® Purple Haze™ model overboot is knee height, and completely insulated using a special nylon covered, 5mm stretchy neoprene closed cell foam insulation.  The insulation goes 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.

They fit with a wide range of crampon binding styles such as “step-in”, “new-matic/hybrid”, and  “strap-on” crampon bindings.  The toe and heel areas 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. 

A thin rubber paint for added abrasion resistance and additional protection for the stitching is applied on the toe, heel, and lower side areas.  This adds some nice added durability to these key areas, and retains the ability for the overboot to be stretchy.

The closure is in the front using a special large size YKK® HEAVY DUTY zipper, with an insulated neoprene fabric flap underneath to help keep snow out and heat in.

Forty Below® overboots are very easy to repair and maintain.  The common crampon poke holes are easily glued back together.  Please see the info sheet provided with the overboots, and also the Repair Section of this website for more details.

Other uses in camp:  We also use these overboots as a sit pad in camp, as a cover for camp booties to add insulation and keep snow out,  stuff them with extra clothing to make an “L” shaped pillow in the tent, as an “insulated bag” to put water bottles with Forty Below® Bottle Boots™ on them inside to help keep water from freezing as fast overnight, and can also be added underneath a sleeping pad to add extra insulation in areas desired.

ORDERING: Please use the fill-in boxes above to provide information about your boot and we will select the proper size overboots for your boots.   We need your boot Brand, Model, Size, and a measurement of the bottom of the sole from the heel to the toe.  Measure using either inches or cm. 

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.  Please use the fill-in boxes above for ordering.

SIZES: XS-XL to fit from ladies 4 to mens 16 double shelled mountaineering boots.

COLORS: Black, Red.  (Purple and Pink not available at this time, hopefully back again in Spring/Summer of 2023)

WEIGHT:  Lightweight! Only 20 oz.! (560g) per pair size Medium.


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