I first bought the black Montrail Enduro insoles,but the arch was too high, so I returned them and bought these yellow ones. I have a really low arch on my right foot, and I tried about 7-8 different pair of insoles, but these were the only ones I found that supported my arch without rubbing against it. I've been wearing them for a few weeks, and they are slowly taking the shape of my foot. I did not heat them in the oven, and I do not believe this is necessary. I love the heel cup, which acts like a shock absorber, and these insoles are very comfortable without being too bulky.<br />If you have a high arch, I would get the black ones. If you have a low arch, then get the yellow ones. If you don't know, you can guess based on age. Arches tend to fall over time, so the younger you are, the better the odds you have a high arch. Everything goes downhill after 40.<br />It also depends on how much room you have in your shoe or boot. You will need more room in your shoe for the black insoles than for the yellow ones. If you are replacing a low insole with a higher one, your shoe might need to be a half size larger than what you normally wear. I was able to use these yellow insoles with shoes my normal size. I have these in my Ahnu hiking shoes, and will buy another pair for my backpacking boots soon.