Parabolic aluminized reflector (PAR) 38 bulbs control light more precisely. LED PAR lights produce about four times the concentrated light intensity of general service A shape incandescents, and are used in recessed and track lighting. Like all light bulbs, the 30 value represents the diameter of the bulb in 1⁄8 of an inch. Therefore, a PAR 38 is 4.75 inches in diameter. PAR38 LED Replacements: PAR38 is one of the best applications for LED due to its directional nature. LED PAR38 provide similar output and beam profile characteristics while using only a fraction of the power.