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 CULT bearings use a cone of the same shape but a harder steel.
Fits all Campagnolo zonda, eurus, shamal and neutron rear rim brake wheels till present.
Fits all Fulcrum racing zero, 3 and 1 rear wheels till present
Fits Zonda and shamal disc brake front and rear wheels.
Fits fulcrum disc brake wheels except the cartridge bearing ones.
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.