COB = foxtail?

Cheap par meter link?

All the original apogee meters are just fine for white based LED's. And are cheap as most good lux meters. If using a ton of 660nm+...spring for a better if you really wanted. But truthfully with correction factors, isn't necessary at all, and I doubt anyone is publishing things to be scrutinize on that kind of level. And even without them will be close enough for what I'm talking about...just knowing the general intensity at the canopy instead of guessing or relying on someone who has never used anything they are talking about an giving recommendations.

The cheapest...just get a 5$ multimeter and done.
http://www.apogeeinstruments.co.uk/sq-110-sun-calibration-quantum-sensor/


For white leds, and led's in general get the sun (~full spectrum calibrated), not electric(floro calibrated).