Great way to make your shoes more comfortable and warmer for the winter season. They work for Uggs and non-Uggs; I put them in a pair of tall leather boots I already owned by another brand and they provided a nice extra layer between my toes and the cold ground.
I ordered a size 5 for size 5 UGG boots, and it fit perfectly. The only problem is that the boot is a lot tighter after putting the inserts in. I can wear my UGGS, but the extra padding is something to be considered. I don't think the insole in the boot can be removed to accommodate the replacement. It fits into the bottom snugly, and it would be too much trouble to use in more than one pair of UGGS for that reason. I am happy to have these replacements, and they will probably flatten out more over time. If you buy them for another brand, consider that UGGS run small.
I was sad because I thought I was going to have to replace my favorite Ugg slippers after the insoles were worn out, but then I found these insoles! I love them and my slippers feel like new ones! I'm ordering another pair for my boots now.