Don't worry about morticing your hinges - just screw one flap to the jamb and the other to the door to get your installations done quicker. The knuckle is visible as is a small gap where the flaps are - only 2mm thick.
The 51mm hinges are 23mm wide with a 17mm installation area needed.
The 64mm hinge is 24mm wide with a 19mm installation area needed.
PLEASE NOTE - all of these hinges are sold individually, not as a pair.