They are definitely heavy duty with the tines doing their work and showing no signs of bending during aggressive dragging of my acreage gravel driveway. They did exactly what I needed them to do which was break up and level out the driveway. The only reason I gave it a four instead of a five was due to the fact that the tines were a bit fussy getting them into place, facing backwards, but once in place they stayed there and worked great. I have seen other models where the tines are more locked into place so depending on the direction you pull the drag harrows, connect the drag bar to one end or the other, so the tines locked into a forwards or backwards position, you get different levels of aggressiveness. With the facing forwards version being the more aggressive, this set of harrows can only be positioned with the tines facing backwards. To achieve a more aggressive pull I fastened a tire to the top of the harrows when dragging.