I use these insoles almost exclusively now for heavy loads (75lb packs and over). Thermoformable "custom" insoles all have the same problem over time- they start to collapse in the arch, and in the heel cup, based on how you walk and what you walk on. If you look at the underside of the insoles, you'll notice a bunch of small plastic strips. Those individual pieces do a remarkable job of supporting the tendons on the underside of your foot. Any of you who have had plantar fasciitis know how damaging and time consuming an injury like that can be.

The insoles are quite wide upon first inspection, which does take noticeable volume out of the shoe, so size boots and insoles accordingly, paying close attention to the sizes, as these are cut-to-fit.

All in all, great product. Don't be fooled by other systems that feel really soft, or by how immediately hard these feel out of the box. They break in quite nicely, and don't absorb much moisture in the top sheet, even after full submersion.