DoubleLux 2ft 16 Bulb T5 Fluorescent LightThe doublelux T5 fluorescent grow light fixture includes high output(HO) bulbs quite similar to the traditional T5 fixtures. The fluorescent bulbs are highly efficient and deliver the same lumen output within the same footprint. You can increase the number of bulbs to increase the lumen output. The grow light comes with UL listed ballasts, which means it meets the nationally set safety standards for usage. Therefore the UL listing makes the