Metra is a metronome application developed for Android and Wear OS devices by RinWave. Its primary function is to provide musicians with a stable, drift-free timing reference during practice or performance. The app is designed to maintain accurate tempo without the gradual timing shifts that can occur with software-based metronomes on mobile platforms. Key features of Metra include a brass tempo dial for adjusting beats per minute, a speed trainer function for gradually increasing tempo over practice sessions, and support for subdivisions to break beats into smaller rhythmic units. Users can choose from four synthesised click voices to match personal preference or instrument requirements. The application also incorporates haptic feedback, allowing the watch or phone to vibrate in time with the beat. On Wear OS, Metra functions as a standalone app, meaning it can operate independently on the smartwatch without requiring a connected phone. Metra is typically used by musicians across various skill levels who need a reliable metronome for exercises, scales, or piece preparation. The speed trainer feature is particularly useful for gradual tempo progression, helping players build speed without sacrificing accuracy. Subdivisions aid in practicing complex rhythms, while haptic feedback provides an alternative to audible clicks in noisy environments or when silent practice is desired. The app requires an Android device running a compatible version of the operating system or a Wear OS smartwatch, and it is available for download from the RinWave website.