iOS 11.3 is a pretty major update, and one of its most notable tweaks is in response to one of the bigger PR controversies to hit Apple in recent times. A few months ago, it became apparent that iOS contains a feature to slow down older iPhones’ processors when their batteries degrade to the point that they’re no longer able to deliver peak performance; Apple says it’s designed to prevent the phones from unexpectedly shutting down altogether.

A lot of people were unhappy with the revelation, and Apple responded by cutting the priceof an iPhone battery replacement from $79 to $29 and pledging to give users the ability to turn off the throttling in iOS 11.3. That ability has arrived in iOS 11.3, which is now available to install. Once you update, here’s how to use it for yourself.

The ability to enable and disable throttling is only available for certain phones, since newer models aren’t affected — Apple says the iPhones 8, 8 Plus, and X all have hardware updates to make such dramatic power management unnecessary. Of course, that doesn’t necessarily preclude Apple from releasing a similar feature in the future, when millions of 2017-vintage iPhones are suffering from depleted batteries. In any case, this iOS 11.3 feature only applies to the iPhone SE, 6, 6 Plus, 6S, 6S Plus, 7, and 7 Plus for now.

Images: Apple

Upon updating one of these phones to iOS 11.3, you’ll notice a new page under Battery in the Settings app. Tap “Battery Health (Beta) and you’ll see a page that starts off with a link to more information about how lithium ion batteries work. Below that, there’s an indicator of your battery’s maximum capacity. If this is under 80 percent, there’ll be a message at the bottom of the screen saying that the battery’s health is “significantly degraded” along with a link detailing how to get it serviced. (You may be in for a long wait.)

If your device has experienced a shutdown due to battery degradation — which could happen with a given battery health of as high as 95 percent — the page will tell you that “performance management has been applied to prevent this from happening again” along with the option to disable the throttling. You can’t turn this back on until you get another unexpected shutdown, at which point it will automatically be re-enabled.

It’s not quite a simple throttle that you can turn on and off as the mood takes you, then. It’s clear that Apple still believes that its default approach to power management is the right one for most users. But if you really want to be sure that your older iPhone is working as fast as possible, the option is now there.