The Makita 619202-3 is the original 9-tooth armature used in compatible BSS501, DSS501 and BCS550 circular saws. This armature meshes with the 35-tooth helical gear to drive the tool and is the earlier version before the later 7-tooth armature and 27-tooth helical gear modification. If the updated 7-tooth version is required, the corresponding armature is Makita 619290-0 and the required 27-tooth helical gear is 227752-0.