No, I'm not referring to this kind of monitor:
Nor this kind:
No, it's this sort:
They arrived yesterday about a month after I won them on eBay - no fault of the seller, as the postmark proved. They're 25mm scale, and pre-painted although perhaps they will get touched up a bit. Before postage, the pair cost a little under £20, which doesn't seem too bad, all things considered.
The black one is obviously modelled on the original USS Monitor. The hull comes in two halves, while the turret wall and floor are moulded separately and the two guns can be slid back and forth on their mountings inside.
The white one, supposedly a "coastal defence monitor", is less identifiable and appears to be of a later pattern with its four tiny enclosed turrets.
The little HLBS steam launch with the figure in it is included to give an idea of scale.
Slightly frustratingly, I'm not actually sure who the manufacturer is. I wasn't able to determine that, but it looks like others may be available.