As a pilot aid to manually synchronizing the propellers, some twins have a small gauge called a synchroscope mounted in or by the tachometer(s) with a propeller symbol on a disk that spins. The pilot manually fine tunes the engine r.p.m.
To assist pilots in manually matching the propeller speeds, certain aircraft models feature a small gauge known as a synchroscope, which is typically installed alongside or within the tachometer and includes a propeller icon on a spinning disk. Pilots then adjust the engine's revolutions per minute (r.p.m.) to achieve synchronization.