Idk i own a par meter and its a big investment for someone and it doesnt really get that much use besides everyone wanting to borrow it hell im not even sure who has it right now. Specially with leds u borrow the forums one and write down measurements and they never really change with t5 u can use to see if par is dropping cause old bulbs but other then the first time u use its really not that important of a tool. Just my opinion coming from a dude that has one that either sits in his closet or someone elses house