I have an 8x8 Palram greenhouse and have used these shelf kits and the stainless steel heavy duty ones. It is true that these ones don't compare in quality to the stainless steel but they are still very useful. These are thinner (in depth) but they work great for holding trays with new seeds. I can fit one tray of 50 seeds on each on these ones and I can fit two trays on the stainless steel ones. So, pricewise, they are about the same (2 of these are equal to one of the stainless steel). I have staggered the stainless steel and these ones and overall they function well together. If you are trying to decide between the two types, then consider what you plan to store. If you expect a lot of heavy items and want to maximize your shelf space, then consider the stainless steel.