Hortilux bulbs have long been considered the best horticultural bulbs on the market. The 600 watt High Pressure Sodium bulb provides 25% more energy in Violet, Blue and Green spectrums than the standard 600 watt HPS bulb. This optimization of spectral energy translates to promote vigorous plant growth. 85,000 initial lumens and a 24,000 hour life-span make this bulb the right choice for the serious grower or weekend hobbyist. This bulb can be used in both vertical and horizontal burning fixtures; must only be used in ballasts that can accommodate 600 watt high pressure sodium bulbs.