A steam dome with a decorative ribbed hemisphere was a signature look for many Locomotives produced by Rogers before the Turn of the Century.
This dome is intended for kitbashing, and can be glued simply on top of any model you might be assembling. It should fit approximately onto a 1/4″ radius boiler for your HO model. There is an additional center locator tab within the dome should you desire to have it placed precisely onto your model: simply align it onto a marked drill spot on the boiler where it is desired. The tab can also be removed using cutters if not wanted.