I would like to know if this block is correct. I'm leaning towards no because when I put the cap on the sensor it doesn't read zero it just jumps between 0 and 18 lux. So I left the cap on the meter and then put it in a black sock that was so black like the inside of a coffin on a moonless night and still didn't read zero. So I removed the battery, then replaced it and reset the device. It still doesn't show zero. I have an inspection area that should be 600 lux. When I put this unit on the table it reads 200-203 lux and then jumps up to 1900 lux. Looks like I'll get a different device. I love Amazon and the internet because the days when a buyer has to be careful are over. Simply click Return Item, print your UPS label, and ship your expenses back to where they came from.