The DJI hub on their 2212 size motors is an 8mm round shaft with two flats on it. A prop that has an 8mm hole in the center will fit on these motors. If you use an APC prop, you need to drill out the front center hole with an 11/32” drill bit, and then press in an 8mm adapter ring into the back side of the prop. This will provide a centered 8mm hole so the prop will fit onto the DJI motor shaft.
The adapter rings do not ship with the APC multirotor series props, but they are available separately in a 6-pack. We carry this part on our website at the following link.