HTC has lined up a run of accessories for the new HTC One max, including the HTC Power Flip Case.
As case is a case, right? Wrong. In this case, it includes a 1200mAh battery, which brings you HTC One max up to 4500mAh in total, which sounds like a weekend's worth of battery life.
READ: HTC One max review
The phone clips into the case, with the battery lying in the flap that covers the front. There are cutouts for the various controls and ports so you can still get to everything, including, bizarrely, the release catch for the back cover.
There are also cutouts around the back for the camera and the fingerprint scanner, so you can still unlock your phone and get into it.
The idea of the case is to not only provide protection for your device, but also to let you open it up and prop up your phone for watching movies, as well as giving you a battery boost.
It's a nice idea, but in the pre-production sample we saw and photographed here, there were a few problems.
First, the weight of the battery in the front cover means it doesn't close particularly well, or sit square when you're holding the phone up. It doesn't magically snap into place, there are no hidden magnets, no screen shut-off or anything else.
Second, the phone wouldn't stay standing up, slipping back down flat again.
However, HTC has confirmed that there will be some modifications before the Power Flip Case hits the shelves to address these two issues.
The HTC Power Flip Case will cost a hefty £79.99, €89.99, $90 when it goes on sale.