This item is an Toro OEM pinion gear. This pinion gear is intended to be used with walk-behind lawnmowers on Toro and Lawn Boy mowers. The metal pinion gear attaches the mower’s transaxle and is used to interconnect with the wheel’s gear to rotate the drive wheel. Fits Models: 10641 (20in Mulching/Rear Bagging Lawn Mower), 10641C (20in Mulching/Rear Bagging Lawn Mower), 10642 (20in Mulching/Rear Bagging Lawn Mower), 10642C (20in Mulching/Rear Bagging Lawn Mower), 10644C (20in Mulching/Rear Bagging Lawn Mower), 10646 (20in Mulching/Rear Bagging Lawn Mower), 10647 (20in Mulching/Rear Bagging Lawn Mower), 10662 (Insight Lawn Mower), 10665 (Insight Lawn Mower), 10665C (Insight Lawn Mower), 10666 (Insight Lawn Mower), 10666C (Insight Lawn Mower), 10672 (Insight Gold Lawn Mower), 10673 (Insight Gold Lawn Mower), 10682 (Insight Lawn Mower), 10684C (Insight Lawn Mower), 10685 (Insight Lawn Mower), 10739 (21in Mulching/Rear Bagging Lawn Mower), 10765 (Insight Platinum Lawn Mower), 10780