The Solarmeter Model 9.6 Red Light Grow Meter is the ideal handheld device for monitoring the intensity and aging of red LED/lamps, red fluorescent and HID lamps, collagen stimulation and wound healing lamps, measuring outdoor red light, and measuring photosynthetic action spectrum red band. Check that brand new bulbs are up to par with manufacturing standards and track their aging to replace them as soon as they're not working the way they should. The simple, one-hand operation of this device makes it easy to monitor red light. Test your lamps with this practical light meter. It comes with a NIST Traceable Calibration Reference Card and runs on a single 9-volt DC Battery, which is included for your convenience.