Isonoe footers have ball bearing feet, what keeps them from rolling off the platform?

With those feet isonoe offering optional sorbothane/glass pads, but i don’t use them. You can try and later you can add those sobrothane pads if you wish. 

Isonoe footers, I just had a look and it appears the bearings are sitting in a recess in the bottom of the isolater. That indent I would presume would limit the ability for them to roll very far. A photo of underneath should clarify the answer to your question.