A headless, cylindrically-shaped item having a straight, smooth, solid body, with or without a drilled hole(s). it has an outside diameter equal to or less than its length. its length must not exceed twelve inches (304 mm); for items whose length exceeds twelve inches (304 mm); see rod, straight, headless. it is used for aligning or transfer of torque and/or thrust, by fitting into corresponding holes of another item. see also pin, straight, threaded.