This is a set of 20 angle lights. I opened all of them and checked that they light up. Each light has 3 LED chips, and the light diffuses softly through the milky white cover. They run on 3 AAA batteries and are advertised to last for 9 hours. To insert the batteries, open the cover on the back, making sure to insert the batteries with the correct positive and negative orientation. Then, firmly insert the tip of the white battery retainer into the hole. If this isn't properly inserted, the on/off switch will be misaligned and won't work correctly. The body color is blue for one light, and black for the rest.