Industry standard worldwide for horticulture. High Intensity Discharge sold with Plus, Agro or Planta lamps which have enhanced blue spectrum for vegetative growth and red spectrum for flowering growth. Reliable and efficient to run. The approximate cost for a 400W HPS on a daily 18 hour cycle is ?35 - ?40 per quarter. All lights are CE certified and guaranteed. Made by leading horticultural lighting companies from Holland and England. All thorough testing and approval worldwide. These lights are far from home-made, unlike other cheap lights on the market. Buying lights without CE Certification is like buying a car without a MOT.