A cylindrical item having a full 360 degree (6.282 radians) complement of teeth on two or more surfaces. it may be a one-piece casting or composed of two or more separate items firmly held together by welding, rivets, pins, or the like, to form a single unit. it is designed to mount on a shaft. for items consisting of a shaft with an integral complement(s) or gear teeth, see gearshaft (as modified). excludes gear subassembly, speed decreaser.