With some slight modifications, they will fit RCBS.
You may have to thin there thickness so they will fit in the slots and or file the flats on the inside surfaces so the mounting holes in the mold will alighn with holes in the handles, they may also may have to be thined on the same inside surfaces just in front of the hinge bolt, you want a lose fit so the mold haves will close properly.
After these mods, they will still work on Saeco molds so go ahead and get you one, you won't be disappointed.