Apogee is the same company, and that is the same sensor that they use in the unit BRS sells, the only difference is you have to multiply your volt reading (mV) by your sensors multiplier. In my case the multiplier is 5 ( the sensor comes with a tag that tells you the multiplier ) so if i get a reading of 79 mV on my meter, its 395 PAR. The Unit that BRS sells just does the math, and display's the PAR.