I have some of these.
They are brass and are actually very good.
I was dubious about them so,,,,,,,
I bought from a renowned luthier some high quality machines for just over £100.
Quess what,they were EXACTLY the same as the Ebay ones for 35/40 quid.
Cant remember the luthiers name ,but even after VAT etc ,I bet I coud've saved £40 or so buying from Ebay.