Runwin LED PAR Lamps are highly intensified type of LED bulbs that illuminate a limited area. PAR20, PAR30, PAR38 are the most common models in this bulb family. Here PAR stands for “parabolic aluminized reflector”, which is normally with focused and narrow beam angle. And the number follows means diameter in inch, like for PAR38, 38 = thirty-eight eighths of an inch, or 38*1/8" = 4.75" = 120.65mm.