I just recently purchased a Jackson Spectra Pro SBP IV bass guitar, and I'm trying to familiarize myself with the bridge so I can properly intonate and set it up. I have attached 3 pictures showing the different tiny little Allen head screws on the bridge. I know the screws circled in red are for moving the saddles back and forth, and the screws circled in blue are for adjusting the string height. What I am wondering is what the screws in the final picture that are circled in green do? Are they just there to lock down the height adjustment part? Sorry, but I don't know the name of the the black part that the strings actually sit on. String retainers maybe? The pictures I've included should make answering this question a bit easier I believe. Thank you to everyone and especially to whoever answers this for me!