This is a key for various models of late-1990s SUN Enterprise servers. At least, that's my guess. I don't have a compatible server to verify, but it looks correct, based on various other listing photos. It's a very simple key, but of course the key isn't exactly the primary means of securing a server.
I've been using this key as a keychain for some years, so it is pretty heavily worn. I've cleaned most of the grime off, however.