I have googled all teams, but do not understand well from the result
Finger Followers? (I see many website talk about rocker arms, but what is finger follower? Are they for different types of engine configuration?)
Lash Caps & Lash Disks?? (Are they put between the valve and rocker arm, but why are caps and disks? And how to hold them in place?)
Seat Inserts?? (I have no clue at all. I know what is seat for valve. Is "seat inserts" something between valve and seat?)
Pictures, websites and any sources are welcome.