PAR is a word used to describe the parabolic reflector light bulbs used in various spot and flood lights. Often, the instrument holding this bulb is a thin aluminum cylinder -- and so, they are often called par cans. These are often the base of a lighting system.

PAR is also a unit of bulb measurement. In that system of lamp identification the first number listed denotes the maximum diameter of the lamp expressed as a number of 1/8's of an inch. For example, some common sizes are PAR-64's (8") PAR-36 (4.5"), PAR-38 (4.75"), PAR-46 (5.75"), and PAR-56 (7").

PAR has no intentional relationship to the point or the pica, though they may seem similar.

The letter at the begining of the bulb code denotes the basic shape of the bulb such as:

The clearer the glass, the narrower the beam is:

  • VNSP - Very Narrow Spot - Totally clear lens.
  • NSP - Narrow Spot - Pebble-ized (frosted) lens.
  • MFL - Medium Flood - About 8 lines per inch of lens.
  • WFL - Wide Flood - About 11 lines per inch of lens.

Taken from a post by Ron Hebbard from the Pro-Lighting forum. I thought someone might find it useful...