Universal Trimmer Gear Box Kit for use with most brands and models of Brush Cutters & String Trimmers. Fits trimmers from 20cc to 40cc. Has 10mm x 1.25 LHM arbor for trimmer head mounting, same as used by Echo. Kit Includes mounts using included adapter bushings for the most common shaft housings, 24mm, 25mm, 25.4mm, 26mm. Replaces: STENS 390-600