I really love the Z-Coil brand. This is my fifth pair. I've been buying them since the day they were available and even had stores in the mid 2000's. The build quality is amazing, the shoes themselves last for years and even if the base of the spring comes loose you can either glue it back on or just order a new spring. The laces are rubbish. Mine didn't last more than two weeks. The laces are too thin. I also bought mountain boots and they had the same point of failure. I also recommend buying gel insoles. It is difficult to stand on the hard plastic base when using the provided insoles. With spare laces and comfortable gel or foam insoles, you'll feel the difference. My knees don't hurt, now I can walk on a treadmill without damaging my injured spine. Great deeds really consume Imoact. Stay away from extension cords or get protective cases. I only use one pair at work. I've found that all the nurses in my area seem to use them as well and stand for hours at work. Finally, I wonder why they are currently classified as medical devices. They've been gone for years, so how about an available version. I love the shoes no matter what.