This item can only be installed by welding. Need because of feet issues on slab floors. Bought it and 3 months later doesn’t work. When they arrived I put them on and where them say and night when in the house. So it could have more to do with the technology than the units themselves. at a time and they are as comfortable as a $60 pair of muffs should ever be. They can hold a ton of weight. You really feel so clean when you are done. easy to install, comfortable, no smell, soft to wear, After I received it I wore it and I realized I made a good choice.