These are very good shelf brackets in every way but one. You cannot use them to hold shelves that support more than 20 pounds per bracket. Therefore they are medium and not difficult. That issue aside, these are very good, quality mounts that will work well in a home or shop (provided you don't overload them). If you want heavier mounts that look similar these are available and have raised sections. in corners for extra strength and resistance to bending. I have them too, but they are much more expensive.