PAR stands for Parabolic Aluminized Reflector.  These bulbs have a reflective surface that helps produce a more controlled light beam. LED PAR bulbs are often used for display and accent lighting, recessed lighting, and movie lighting due to their ability to project directional beams using only a fraction of power. The number on an LED PAR bulb refers to the diameter of the lamp measured in eighths of an inch.  To determine the size of a PAR16 bulb, simply multiply the PAR number “16” x 1/8 (0.125).  In this case, a PAR16 bulb is 2 inches in diameter.