It has a thread and screws into a recess at the back of the prop. I presumed that all the 38’s had the same system but not sure about other models. It was all news to me of course until the first haul out when some old codger tapped it with a spanner and said “that props had it, you should have screwed an anode into the back.”
They are now 25 Euros each which is a lot of money for something that size, but I believe the Chinese are buying up all the zinc they can get hold of so the price will go up and up. However when my Nauticat was commissioned in Hamble unbeknown to me there was not an anode fitted and on the first haul out the prop had to be replaced, so they are absolutely essential.