Need to switch to HPS for the fruiting and flowering phase of your plants but only have a metal halide ballast? The EYE Hortilux 62550 360 watt HPS conversion lamp is just what you need! This unique bulb is engineered to operate on a 400 watt M59 core and coil metal halide ballast. It produces 45,000 lumens of 2100K (red spectrum) light without the need for a costly new ballast or rewiring of any kind. Even better, with the proven reliability of the Hortilux brand, you'll be able to reap the benefits of this versatile lamp for a long time to come.