The Sunmaster Premium Metal Hallide Lamp is a high quality bulb for use during the grow phase. Sunmaster have poured all of their expertise on lighting into this lamp and the end product shows it. Tweaks to the colour temperature mean the blue output is superior to other halide lamps. In fact, the Sunmaster Premium Metal Halide Lamp has up to 30% more than some other brands. Sunmaster recommend that these lamps perform best with a high frequency digital ballast.