I just received the latest iteration of Apogee's MQ-510 PAR meter. The sensor is now blue to indicate it is the best to use for LED (and other) light sources. Apparently this was done to avoid confusion when dealing with multiple sensors in research applications. Although I own a $1,500 Li-Cor meter and underwater sensor, this Apogee unit is my go-to device. This sensor is cosine-corrected and fully submersible. The meter reports PAR that is corrected for the immersion effect. What I really like is how easy it is to log light intensity data. It takes measurements every 30 seconds when in log mode and averages these every 30 minutes. It can store 99 averaged measurements. This is what PAR (or correctly, PPFD) looks like in my reef tank. Love this meter!