When purchasing levelers for any corner cabinet, make sure to add an EZ-Susan in the rear. This gives you the ability to lift the far back corner with ease... and keep it from sagging.
The photo is showing (1) EZ-Susan mounted to the bottom of a corner cabinet. The cabinet is upside down, so you can see the leveler.
With the EZ-Susan, we now level the Rear Corner first... then the other rear levelers. Then... simply adjust the front feet till they touch. NOW... leveling Susans usually takes less than a minute!