This is well built very sure it will hold up to years of use. I needed a side to pull from and the additional handle was a perfect fit. I haven't tested the load capacity, but initial tries very sure it will meet them. The three rib rim sticks quickly and the cup holds even after pressure release. I tried it on slightly curved glass and it worked as well, easily works on auto glass, windshields. It quickly pumped up only 4 or 5 needed. The rubber feels like it would work on uneven surfaces but haven't tired that. Quality product for the money

Really bigger than expected but overall works

I bought these so I could move large glass panels 94”x40”x9/16 weighing at 150lbs plus each. These cups made the job so easy by providing a a place to grip and carry. I have an older set using as well but these ones are excellent, tough and durable. I recommend this.