The HB-RE124 is the special steel bearing cup used on all Campagnolo and Fulcrum hub with;
1) a 17mm diameter alloy axle same cup has been in use since 1999 for these type of hubs.
2) "cup and cone" steel bearings
The hubs with USB or CULT bearings use a cone of the same shape but a harder steel.
Simply remove the old cup and press in the new one. Cyclus make the correct tool for the job. If you love the perfect tools just ask and I will supply this for you.