The RTR-574 wireless, four-channel data logger from TandD monitors illuminance, UV light, temperature, and humidity. The logger can also display cumulative illuminance and cumulative UV light. The luminosity range covers 0-130 k lx, and low-light resolution to 0.01 lx. The UV range covers 0-30 mW/cm2. Internal accumulation of exposure is for both light and UV. The device has a range of 10-99% relative humidity along with an expanded temperature range of 0-55°C. The 2x3-in unit operates on one AA battery. Data capacity is up to 8000 readings for four channels, for a total of 32,000 readings in one-time or endless recording mode.