The diameter of the GN HAT flange is smaller than the diameter of the DIRECT flange, therefore the HAT flange will work either rotor mount application, but the DIRECT flange will only work with direct mount rotor setups.
"DIR" Refers to a hub assembly that uses a rotor adaptor that bolts the rotor directly to the back of the hub. "HAT" refers to a hub assembly that uses a rotor and hat assembly that slides over the outside of the hub to mount to the rotor.
Be sure to give the two countersunk retainer screws a liberal dab of grease or anti-seize compound.