Mobvoi’s TicWatch Pro is going on sale today for $250, after being announced back in May. The TicWatch Pro puts a new twist on Wear OS smartwatches by adding in a second, low-power screen that’s meant to keep the watch running longer.

To make this trick work, Mobvoi placed a transparent FSTN LCD display (picture a traditional digital watch) on top of the watch’s primary OLED screen. The OLED screen is used to show the standard Wear OS interface. But when you aren’t using the watch, the OLED screen turns off and you’re then able to see the LCD above it, which displays the time and other information you might want at a glance, like fitness data.

Mobvoi estimates that you’ll get two days of battery life using the watch this way. When battery life is low, the watch will also prompt you to enter “Essential Mode,” which uses only the top display and some key sensors, while turning off Wear OS and all of the smart features (like notifications) that go along with it. Mobvoi estimates you’ll be able to get an additional three days of use out of the watch that way. Or, if you really want to, you can use it exclusively in Essential Mode from full charge and go for 30 days.

The TicWatch Pro pulls off a neat trick, but I’m not sure how useful it’ll actually be in practice. You have to fully boot up Wear OS every time you want to switch out of Essential Mode and use the watch’s more advanced features. That takes a full minute, so it’s not something you’ll necessarily want to be switching back and forth between just to squeeze in a bit of extra usage. And, of course, you miss out on a ton of features, which are presumably what you bought the watch for.