Simple bases that clip on and expand the 'size' of your miniature. Used for standard inch
scale bases / 28mm scale / heroic scale miniatures. (Such as those found in the pre-painted sets that are sold.)
If you have a 'flying' whatever, then you can use the flyingmod part as well as a high base to sandwich the mini's original stand.
Low bases on the other hand work well when a mini's foot or other item extends beyond the base itself.