Just for clarification, It's a Photo Clam ballhead and Photo Bert is the dealer. Photo Bert is well known for their cheat sheets and is a member and advertiser here at Nikonians.
For what it's worth, don't put any emphasis on the weight capacity - there is no standard for measurement and no lens and camera combination that weighs that much. Furthermore, unless all system elements can support that much, it makes little difference. The fact is even 10 pounds is very hard to balance on small head regardless of the amount of locking force.
Photo Clam has a number of users with positive reports. I would not expect the same quality as a top of the line head, but the cost tradeoff might be okay - especially on a tight budget with mid to lower priced lenses and other gear. If you are using pro glass, I would not compromise on a ballhead.