Although modern phone batteries seem to get bigger over time, they still drain at a rapid pace due to the increasingly powerful hardware they contain, as well as the performance-hungry apps many users run on them.

Apple attempted to mitigate this issue with the launch of the iPhone 6's "Smart Battery Case." The case acted as an extra layer of protection for the phone as well as a battery booster. By plugging the device's charging cable into the case, users could charge the case's battery and the phone's simultaneously.

The company released a similar case for the iPhone 7, but it has not shipped any more of the cases for its flagship phones since. Whether that's due to poor sales or merely a lack of interest on Apple's part, we may never know.

Regardless of their reasoning at the time, it seems that Apple could be planning to bring the cases back soon; at least, if a product merchandising guide acquired by Appleosophy is anything to go by.

The guide, intended for the eyes of retail workers alone, reveals two cases for the iPhone Xs and Xs Max. As spotted by MacRumors, both appear to have the same battery "humps" that the iPhone 6 and 7 Smart Battery Cases did.

If Appleosophy's merchandising guide is accurate, that means we could expect to see the Smart Battery Cases finally make a comeback, though we don't have a specific release date or release window yet.

Image courtesy MacRumors