Lumens/Foot Candle :
Measures the amount of light output provided by the lamp. The more lumens,/foot candles the more light provided. Lumens are measured at the light source and foot candles are measured at the object.
Center Beam Candlepower. This is the brightness, measured in candlepower, at the center of the beam pattern. A spot light and a flood light can emit the same total light (the same lumens), but the spot light will have a much higher CBCP than the flood light.
This is the degree of the angle of the beam of light.
Measures efficiency. The rate at which a lamp is able to convert watts (power) into light (lumens), expressed in lumens per watt or LPW. LED lamps are above 50 LPW and some approach 100 LPW.
Correlated Color Temperature. This represents a lamp’s Kelvin (K) rating. Just as with halogen, incandescent and CFL, LED products provide specific Kelvin ratings such as 2700k, 3000k and beyond. Lower numbers are warm colors and higher numbers are cool colors. For example, warm white ranges from 2700k to 3000k, while cool white ranges from 3500k and up.
Color Rendering Index. Measures the effect a light source has on a perceived color of objects and surfaces. High CRI light makes virtually all colors look natural and vibrant. Low CRI causes some colors to wash out. LED light sources provide a high CRI of 80 or more.
The life expectancy of the lamp. The term L70 represents 70% of lumen output remaining after the life of the bulb. Most LED lamps are rated to allow for 30% loss of lumen output from the point of installation until it is no longer used. Manufacturers will rate the longevity of their lamps accordingly to the quality of components used. The LED industry range is from 25,000 hours and up. The majority of LED lamps are rated for 50,000 hours, but some products can last a lot longer.