View through the caseback to the movement of the Omega Speedmaster ‘Super Racing Co-Axial Master Chronometer Chronograph

Figure 6. The stiffness of the balance spring’s spiral and Blade
components separated out. With the Blade in compression, spring overall stiffness is lower than with it in tension.

Figure 4. Details of the Spirate calibrated rate adjustment. The Rate Mobile Stud Holder follows the snail cam’s motion. The stud descends below the cock, grasping the tip of the balance spring’s Loading Beam.

Figure 1. The Spirate balance spring. The Loading Beam Tip can be moved left or
right to introduce tension or compression at the Blade, altering the rate of the watch.