First of all let me share with you that this purchase was a BIG frustration for me because the seller DID NOT send the complete product. They send me only the dolly skate and its carrying briefcase, but NOT the camera ball head mount, so it it useless now to me. You should know that Konova does not sell the ball head mount separately, this is the first dolly I purchase, so I don't know if the center screw will take "any" other base mount. And if I ever find another ball head mount, it'll be at an additional price. So be aware that if by any chance you loose or break the ball head mount, Konova doesn't have replacement part for it, either you find a univeral ball head or buy the whole package again.
But about the actual quality of product, I can only comment about the the dolly itself, very well designed, its material is strong and it runs quietly over any surface, its wheels does not make a single sound.
I rated it 4 stars for the proprietary ball head mount. And 1 star for the awful experience with my purchase. :(