Specification: Note: Options A, B, C .... etc. stands for the corresponding A, B, C gears within the picture, choosing A means shopping A gears, and so on. Thank you. 1.Applicable To Motor Shaft Of 550 / 775 Model, Usually Used for Lithium Battery Motor Electric Hand Drill Motor Shaft 2.Number Of Teeth: 6/7/8/9/11/12/13/14/15/16 Teeth 3.Hole Diameter:3/3.9/4.9mm Package Include: Motor Gear x 5pc