These PWR INSERTS work with Inception Designs and Planet Eclipse backs that are designed for PWR INSERTS. They do not work with other systems from other companies. The new system uses specially designed inserts that maintain all the easy ball entry features of the Stella backs. This allows the use of a single outer back that can be more cost effectively matched to the marke and it's anodizing yet maintains all Stella performance features AND is available in many sizes.