Description:  Silver Streak Pro Spur Sprocket .325" Pitch, 7 Teeth Replaces OEM: (Please be sure of your OEM part number before purchase)  For Carlton: 6-100961X, For GB: ST305-J7N, For Oregon: 106657X, For Ref No: SST305-27N, For Stihl: 1123 640 2015, 1123 640 2074, Fits Models:  For Stihl 017, 018, 018C, 019, 021, 023, 023C, 025, MS170, MS180, MS190, MS210, MS230, MS250 and MS250C Specs:  Crank Diameter: 10 mm Pitch: .325" Teeth: 7 Bearing included