Servos are powered by the ESC's output to the receiver. If you're using a higher-strength servo than the ESC can support (usually greater than 20kg), you may experience 'brown-outs' where the radio signal can be interrupted and cause erratic driving. This can be helped by plugging a Glitch Buster into the receiver smoothing the current delivery. However, in some cases, you may need to install an external BEC. Power HD Micro 1711A Servo SpecificationsTotal Height (A ) = 30mm. Body Width (B ) = 23mm. Below Mount (C ) = 16mm. Above Mount (D ) = 14mm. Total Length (E ) = 32.5mm. Total Width (F ) = 12mm.