Grower's Choice 10K 500 Watt Single Ended CMH BulbGrowers Choice final phase 10k CMH finishing lamp should be used during the last week to two weeks before harvest and is specifically designed to emit photons mainly in the ultraviolet 350 425 nm wavelength. As high amounts of UV light causes damage to plant cells. In order to protect themselves and to facilitate reproduction, plants compensate by releasing more resinous oils which translates into a higher quality yield. Grower's Choice 10,000K 500