System Blue brass instruments have Graduated Tuning Guides. The guides themselves do not affect the horn while you are playing and performing. The GTG’s come into play after you’ve started to learn your tendencies in different temperatures and playing environments.
When you are in your practice room, and you have gotten yourself in tune and centered, jot down where the tuning slide is for future reference.
Doing this in every playing environment will get you “in the ball park,” closer to being in tune and centered, so you can get on your way to practicing and performing sooner.