Coolant plugs for some reason, I have no idea why they are there to be honest, maybe somebody smarter than me knows.
I say replace them because I can guarantee you, it really pisses you off when you are just getting ready for the first fire up and you got coolant leaking out of them. Then the whole top end has to come back apart to replace them. This happened on the first motor I ever put together, every one since gets new plugs