The associated blurb does suggest it is brass and is ornamental.
"A rate opportunity to acquire a limited edition,
ornamental brass windlass.
I acquired the remaining stock of the Dunton Double windlasses from the estate of my deceased cousin who designed and manufactured them.
I've sold all bar a few of the aluminium type but have around a dozen of these brass units. I'm not sure if they are meant to be functional or just ornamental but they are certainly a thing of beauty, particularly if you're interested in all things canal related. For comparative purposes the aluminium DDs weigh just under 600g while the brass weigh approximately 1400g.
This particular 'Double Double has been in dry storage for several years and, although it's new, I'm listing it as old stock and seconds, because, while the finish is good there are some blemishes."