The ECHO A556000172 is a genuine OEM pinion designed for various ECHO outdoor power equipment models. This small gear is crucial for transmitting motion and changing rotational speed within the gear case assembly of trimmers, edgers, and similar machinery. Replacing a worn or damaged pinion with this authentic ECHO part helps restore proper gear case function and ensures reliable equipment performance. It measures approximately 12.7 mm in length, width, and height, and weighs about 0.023 kg.