it clamp force as strong as expected.
The shape of the magnet that I received is different from the image on the web site. They told me it is not updated by manufacturer in China. You can get exact the same magnet ( the one that I got ) from Amazon for less than 20 bucks. It is too big for my project so I put it aside for now. However there is nothing wrong with it just the different shape and price. It is very strong magnet force to clamp down anything. The company has a policy to return but I decided to keep it.