1.First remove the BEC connector of speed controller and then put through magnetic ring. 2.Put the BEC 3-wire through the magnetic ring and wind for 4 times as photo. After that, put the BEC connector back. Instruction: - Apply to BEC output wire of ESC, to avoid the high frequency harmonic to interfer the receiver caused by the motor. Specification: - Magnetic ring x 3 - Size:7.9x12.7x5mm - Weight:1.8g