PowerVEG Colors provide nanometer specific spectrums to further enhance the PowerVEG Full Spectrum + UV (FS+UV) grow lamp during the vegetative and flowering growth cycles. Combining the FS+UV with the Colors allows for structurally sound plants ready for transition to HID where bigger and better yields and more overall production will be seen. Comes in four colors: 420 provides the most crucial spectrum needed during the veg cycle, 460 bridges the gap between the vegetative and flowering stages, 633 promotes vertical plant growth and expands leaf size and 660 is a true flowering lamp, it maximizes the flowering process.Eye Hortilux