There are 3 options for back adjustments on the Ignition Chair: Standard Tilt, Synchronized Tilt and Synchronized Tilt with Back Angle Adjustment. Regardless of which you select your new chair will have the ability to adjust the tension when you lean back, tilt lock (prevent the chair from leaning back) and adjust the height of the back, which puts the lumbar region of the back where you need it.
Standard Tilt: Very basic. The pivot point for tilting is directly above the center of the chair base and reclines at a 1 to 1 ratio, meaning the angle of the seat and back are the same. Also, the tilt tension knob is located under the front of the seat, not on the side of the chair where it would be easier to adjust.
Synchronized Tilt: The pivot point for tilting is still in the same spot but the back reclines at a 2 to 1 ratio to seat angle. It allows you to recline while keeping the seat cushion relatively parallel to the floor. The tilt tension knob is conveniently located on the right side of the chair.
Synchro-Tilt and Back Angle Adjustment: The back angle adjustment is very unique and many people buy this chair because of it. What it does is allow you to lock the back in an infinite number of positions and remain leaned back even when you go to lean forward. All else is the same as Synchronized Tilt.
Please note: folks that opt for the standard tilt end up exchanging their chair for one with the upgraded tilt more times than you would imagine. It is the #1 reason for return/exchange on office chairs. When in doubt, choose these better options as you can't add them later.