I buy these by the hundred:
https://na.suzohapp.com/products/accessories/26-1528-00
Pinball Life's product is a LOT better... IF you want your pinball to slide! The bottom of pinball life's leg leveler cup is smooth. It allows you to slide your pinball out from the wall for service, and to nudge your machine better.
Happ is made from a different material (rubber, or rubber-like), and has little rings that grab the floor better. Very hard to nudge your pinball.
Leg levelers can have the center 'peg' actually deform the metal of the leg leveler. This puts the weight of the machine on a peg point instead of distributing it on the whole foot of the leg leveler. If you notice the center of your leg leveler is 'pooched out', replace your leg levelers.
Pinball Life's leg levelers are not only shiny chrome, they are better quality (IMO) than what Stern puts on their machines fresh out of the box:
https://www.pinballlife.com/heavy-duty-leg-leveler-with-nut.html