I tried for a while in my new hiking boots. I did not heat mold them as the packaging said that they would over time mold to your feet without the heat molding. They seemed ok but the base had a slight ridge that put pressure on the outside of my foot. They also seemed to increase pressure on areas where I have high contact, thus causing callouses to build/increase in size. I switched to a different insert that turned out to be more comfortable and better suited for my feet. I am not sure if I will give these another chance.