Apple is working on interchangeable AirPod headphones that come with health tracking features to measure heart rate and stress levels.
That's according to a new patent filed by the firm which reveals how a new version of its wireless in-ear headphones would be able to fit in either ear.
The filing shows the device slipping into the ear canal and being held in place with a bendable band.
Apple's current wireless AirPods were first launched in 2016, although some users have complained they can easily fall out or become uncomfortable.
Apple removed the headphone jack from its iPhone models from the iPhone 7 onwards, forcing users to buy wireless headphones.
While Apple users may be hoping for a redesign soon, companies often file patents as part of research on new devices, although the designs could be far away from launching or never be released.
The patent for the earbuds, first reported by 9to5Mac, could also see biometric sensors built in to the device. While this could be used for modifying the audio users hear, it could also include electronic or LED sensors for recording health data.
Apple's patent said some of this could include measuring the "heart rate, blood volume and respiratory rate" as well as temperature and stress levels.
It could also be used to perform an electrocardiogram (ECG) scan for electrical activity in the heart. Apple recently added ECG scanning to its Apple Watch devices and has made health tracking a major selling point of its wearable technology.
Apple is said to be in the process or upgrading its AirPod headphones for 2019. Analysts have predicted a fully redesigned version to go on sale in 2020.
Apple had planned to release a version of its AirPods with a wireless charging case, although it has gone silent on the plans for over a year. A wireless charging mat, the Apple AirPower, is said to have been delayed due to overheating problems.