High Intensity Discharge Base Type (Not Actual Size)
High Intensity Discharge Bulb Shapes (Not Actual Size)
The size and shape of a bulb is designated by a letter or letters followed
by a number. The letter indicates the shape of the bulb while the
number indicates the diameter of the bulb in eighths of an inch.
For example “T-7” indicates a tubular shaped bulb
having a diameter of 2 1/8 inches. The following illustrations
show some of the more popular bulb shapes and sizes.