I have 2 fans I am trying to replace I do not see any part numbers on them. I found a listing on the internet that matched the same size and the photos looked the same so I bought them and then I was told they were out stock. These fans fit a ASRock A75 Extreme6.
Why do you need to replace the fans?
I do not know what they are, but measure the size to find a equivalent replacement.
Also look at the fan connector. It couild be 3 pin or 4 pin; you want to match that.
You will have the option of several speed versions.
Well, what was the listing you found that was out of stock? That would be useful information.
Given the dirtiness of these fans, I'd be inclined to just replace them with two matching. They're so scummy that even a new one of thise identical fan wouldn't look like it matches the old one that still works.