This is the main reason I don't buy cheap watercooling gear from sites who are not known for carrying good watercooling gear. You would get good documentation and mounting hardware for well-known watercooling hardware vendors.
That block looks like its modeled after CPU blocks from 10 years ago - large 'pins' rather than micro channels, no directional plates or internal flow pattern for flow over the die, etc.
Not saying it won't work fine, I do question build quality, the lab testing done and validation on sustained use/performance that most good companies perform on blocks.
What product are we looking at? Can you provide the actual Amazon link?