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  • Providing superior load support and comfort, this gender-specific hipbelt is made with 3-D dual-density foam that is contoured and anatomically shaped
  • The foam technology in IsoForm4 CM hipbelts allows heat-molding for a custom fit
  • Osprey's certified Custom Molding available in most stores—check your local REI store for a custom hipbelt molding oven


View all Osprey Hip Belts

REI membership


Best Use Hiking
Fits Waist/Hips
27 - 31 inches
30 - 34 inches
33 - 37 inches
36+ inches
Material(s) Heat-moldable foam/nylon
Weight Unavailable
Rated 3 out of 5 by from Not Compatible with older Aether seried Recently purchased as a replacement for my 2009 Aether 70L. Not much information out on Osprey ' site or the interwebs as to compatibility and limited side profile pictures to clue one in on compatibility. Just a warning, the IsoForm4 is only compatible with 2013 and newer Aether series. Not a huge issue, will just have to exchange for the regular IsoForm.
Date published: 2015-10-01
Rated 5 out of 5 by from Kelty external frame rucksack upgrade I use a Kelty Yukon and a Gregory Baltoro 70. and decided to upgrade the Kelty's worn hipbelt with the hope of making the Kelty as comfortable as the Baltoro. REI had the Osprey belt in stock and it appeared to be workable. I used a leather patch, contact cement and a single 1/4-20 bolt with washers and a locknut for a single point of attachment that allows some movement as I walk. I've carried 30 lbs and so far it works great and well worth the expense.
Date published: 2014-08-08
Rated 5 out of 5 by from Unbelievably good upgrade to High Sierra pack I have a High Sierra Sentinel 65L pack that I've been trying to get dialed in for years. It has never been comfortable, even with lighter loads. I found that this hipbelt would work with it, so I swapped it in and can not believe how much of a difference it has made. With this hipbelt allowing me to get a proper fit, I am now able to hike several miles with no pain whatsoever.
Date published: 2017-01-19
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Does this belt fit on the new Aether Anti-Gravity 70 liter pack?

Asked by: RBJones
This hipblet is not compatible with the new Aether 70 AG. The IsoForm5 CM Custom Moldable Hipbelt is a better fit.
Answered by: REIservice
Date published: 2017-03-24

Will this hipbelt go out of stock now that the Aether Ag has come out? I'll need a medium in the near future...

Asked by: Matt
The 2017 Osprey packs use the IsoForm5 hipbelts. We will continue to offer the IsoForm4 while supplies last, but cannot provide an estimate of how long that may be.
Answered by: REIservice
Date published: 2017-04-07

The XL states 36"+ so will it fit a 54" waist? What is the maximum waist size it will fit?

Asked by: old engineer
​The XL fits a maximum waist of 57".
Answered by: REIservice
Date published: 2017-05-01

Does the Osprey IsoForm 4 CM custom moldable hipbelt work for the Osprey Atmos 65 backpack and Osprey Stratos 36 day pack as well as the Osprey Aether backpack, which is identified in the project information? I'm looking for better back lumbar support.

Asked by: Trekker Glen
This hipbelt does work with the Aether, but it does not work for the Atmos or the Stratos as those packs do not have interchangeable hipbelts.
Answered by: REIservice
Date published: 2017-01-05

Will this fit and work on my Crescent 90?

Asked by: linowilly
This hipbelt is only compatible with the Aether and Xenith series packs from Osprey.
Answered by: REIservice
Date published: 2017-03-14

Will this fit the Ariel 65? Looking to replace the hip belt for a women's bag, but need a little more than 36". 

Asked by: Shamilog
This hipbelt is compatible with an Ariel 65 pack provided that your pack is the model with the hipbelt pockets.
Answered by: REIservice
Date published: 2017-01-05
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