The Apple Watch will be getting solid state buttons that don’t move up and down but rather sense the touch of a finger, a source with direct knowledge of Apple’s plans tells Fast Company.

Apple will stick with the Watch’s current button configuration, with a button and a digital crown situated on one side of the device, but neither will physically click as before. Rather than reacting to the user’s touch by physically moving back and forth, the new buttons will vibrate slightly under the fingertip, using the haptic effect Apple calls the Taptic Engine. (The digital crown will still physically rotate to navigate through content.)

The switch to solid state buttons in the Watch is similar to the conversion of the iPhone’s home button to a solid-state design in 2016’s iPhone 7. In past years, other Apple components such as MacBook trackpads and iPod control wheels have also gone from moving parts to solid-state technology.

The new buttons could be part of the new Apple Watch the company will announce this fall, or, if not, will be included in the 2019 Watch, the source said.

Solid-state buttons will make the Watch more water resistant because the opening needed for a physical button is eliminated. The solid-state controls also take up less space in the design, freeing up room for a bigger battery, the source said.

Apple has also been working on using the top of the buttons as sensors to gather health-related data such as heart rhythms. The heart-rate sensor on the back side of the watch does this through direct contact with the skin, but some types of measurements require more than one point of contact with the user’s skin. The top of either of the new solid-state buttons could provide that.

Longer-term, Apple’s industrial design group has been working toward a future Watch that has no buttons at all. Rather, specific areas on the side of the device would respond to finger touches. That direction would be in line with the company’s long-held desire to streamline physical features out of its devices altogether, as seen in the elimination of the headphone jack in the iPhone 7 and the home button in the iPhone X.