I have used them on several ocassions and have been pleased with the results. As stated earlier, the ground surface must be level. I prefer the EZ Pad. It only has 4) 4'x4' Foot Pieces, which fasten together with strong brackets. The Ez Pad has a strong extruded design. You can build the base, then easily carry it to the proposed area or flip it over in place. Goodluck.