Sunmaster High Pressure Sodium Bulbs are a full spectrum bulb. They emit more blue light than regular H.P.S. bulbs. This will allow you to give your plants the light they need for flowering while still being able to grow plants in the vegetative stages without stretching. Ordinary high pressure sodium bulbs do not emit light in the blue and violet spectrum. If you are going to use only one bulb for both vegetative growth and flowering, you should use an enhanced spectrum bulb. They also help to keep the plants from stretching in all phases of plant growth. These bulbs are available for 1000 and 600 watt ballasts. These bulbs are environmentally friendly.