The adjustable spring determines the amount of force, whereas the 3 holes in the green arm, in  my photo, are adjusted to select the desired depth.  The top hole is used to place fert. the deepest, and the lowest hole is for placing fert. at the shallowest depth possible.  The black casting has slotted holes, and is for adjusting the depth of the boot in relation to the single disc.  As the disc wears, the boot needs to be moved up.  Hope this answers your questions.  You can do a search for your given planter and opener combination.  Deere has a good source of online info for this specific topic.  Good luck with your openers.  We have used these openers on all of our Deere planters, as we do a combination of no til and min til on our heavy soils, and have been happy with the results.