Measure the height, width and depth of your air conditioner with a tape measure. Make a note of these dimensions to use when you order a cage.
Measure the width and depth of the condenser pad and mark this down. If your condenser pad is only slightly larger than your air conditioner unit, buy a cage that is a size larger than your unit so you can mount it into the ground.
Determine what your condenser pad is made out of. If it is made out of concrete, it is safe to bolt the cage to the pad. If it is made out of plastic, order a larger size so that you can mount it into the ground rather than onto the plastic to make it more secure.