Electric chain saw technopolymer drive gear with a 14 splines (fit 12 mm), outside diameter 84, inside 72 mm, height of bell: 23, 59 teeth inside. Compatible with Leader LD 4720, PC 4729 CS 512, FORWARD Garden FCS -1200, -1800 (F18010, F18020) PRO, S180-10, Electric chain saw FCS-1200 PRO F18010, Forward FCS 1200 Pro F18010 chain saw