This product contains 08 HDR environments and 08 x's 3 matching Iray lights, meaning each environment has 3 matching lights for a total of 24 lights. You can control the brightness of your render by controlling the environment with the included settings and lights, each light is labeled a,b,c, "a" being the darker of the 3, "c" being lighter with additional lights added. So many possibilities to mix and match!