Parabolic Aluminized Reflector (PAR) light bulbs are commonly used in office display lighting and are found in outdoor flood lighting in homes or offices. PAR lamps come in a variety of diameters from 2 inches to 8 inches diameter. The diameter of the lamp will be indicated by the number after PAR in the part number. These numbers represent eighths of inches. For instance, a PAR16 is 16/8 inches or 2 inches in diameter. In addition to diameter options, the bulbs come in different beam spreads or beam widths that will determine how the light appears on the object you are illuminating. The more narrow of an angle, the light will appear more narrow or focused. A wider beam spread will disperse the light further, creating a larger but less focused illumination.