The number after PAR will represent the number of eighths of an inch the bulb diameter is. This means that PAR38 RGB LED bulb is 4.75 inches across. For color mode, it adopts RGB, which means the RGB component of each pixel is assigned a range of 0 to 255 intensity values. RGB image using only three colors, you can make them according to different mixing ratio, the screen color reproduction 16777216. In one word, all color is available in PAR38 RGB LED bulb. As a bulb adopts LED as light source, PAR38 RGB LED bulb is featured with high power LED provide long life, which offer clean pure white light and other great color. It is shock and vibration resistant, as well as direct screw-in replacement. This high power LED bulb do not use the older 5mm round LED as used in earlier LED light bulbs. This high powered LED light bulbs use the new super flux SMD LED. L.E.D means Light Emitting Diode, a display and lighting technology used in almost every electrical and electronic product on the market, from a tiny on/off light to digital readouts, flashlights, traffic lights and perimeter lighting. As replacement for traditional general lighting, this kind of LED bulb is suitable for museums, art galleries, cosmetic counters, school, universities, hospitals, conference, meeting room, show room, commercial complexes, factories, offices and more applications.