Raw lumens VS Effective Lumen
Photo-metric testing is used to get an accurate effective lumen number, which accounts for all of the above listed variables, and provides real world effective lumen output. One bulb may have higher raw lumens than another bulb, but it's the bulb that has the higher effective lumens that will be the brightest. So, if you see a set advertised with 8,000 lumens, you now know to not only half that for one bulb, but depending on the quality of the bulb, it can lose as much as 75% of 4,000, putting the effective lumen at 1,000 lumens. Which is only a couple hundred more than the stock halogen bulb. Our effective lumen is 1,800, meaning they lose less lumen as they get hotter due to the highest quality thermally conductive materials.