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Interesting LED Bulb

my guess would be they took the PAR form 5mm away to help sell it and at that price hmmm
 
I won't be cheeky :)

Although we know PAR as a lighting measurement that isn't what the PAR on that light means. You won't find many (if any) bulbs detailing PAR measurements. Its just not useful to the majority and of the minority who want to know, most won't have a clue what the result means because the minority want a measurement at the target area and not source.

For example you could buy 2 tubes and test them at 50PAR next to the light. Useful? Not really. 1 could be 5PAR at the substrate and the other 15PAR just due to the way the light spreads be it because of a reflector or the angle an LED is pointing different to the others etc.

We use PAR meters to test the reading at the target and not at source so a source reading may give us an inkling as to which light performs better but for our purposes it wouldn't help us too much because a higher PAR light may also have a wider angle and therefore directly below it (at target) be a lower reading that a light with a narrower angle but less PAR at source :)

Sorry to ramble I ranted instead of giving the proper answer. lol. In that advert the PAR means Parabolic aluminized reflector. The number represents the diameter in eighths of an inch. Diameter in inches is found by dividing the PAR size by 8. so a PAR38 lamp is 12cm (yes 4.75inches) wide.

AC
 
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