I installed 8 pieces and had to make a compensation plate for each individual support, because the underside is not flat and then also different for each support. The picture in the item description is completely wrong, as the base plate is much thinner than it appears in the picture. The quality of the \ "weld seams \" (is only tacked) is absolutely inadequate for a safety-relevant component. After less than a season, the stiffening on the side of the first support has now loosened (when leaning against it in the harbor). Unfortunately, I drilled through my deck for these supports and am now tied to the hole pattern :-( Conclusion: is no good and is dangerous!
Underside of the foot on the support surface sharp-edged, mounting holes not true to size, just Far East scrap. \ R \ nLesson - who buys cheap, buys twice.