Indoor Sun 1000W 400V HV Pro SE Lamp HV SERIES are lamps which have a voltage as high as 265V, however are known and marketed as 400V. All the Double Ended lamps are HIGH VOLTAGE. They work with lower current (amps) which causes less power loss and lower temperature, resulting in a higher lifespan of the ballast. They provide higher values of PPF & PPF/W than low voltage standard lamps. The HPS PRO HV series is engineered to delivers superior flowering grow light with the HV arc tube inside the traditional bulb shape. The performance is better than standard HPS lamps and close to the HPS DE PRO HV. The 1000W HPS PRO HV is the market leading grow lamp with PPF and PPF Efficacy. PPF (Photosynthetic Photon Flux) is the rate of photosynthesis determined by the small light particles called “Photons”. The unit is micro mole per second. Plants have a completely different sensitivity for colours of light than the human eye (PPF is a measurment of plants’ sensitivity). Plants require PPF to grow, especially in the flowering stage. Therefore a higher PPF value indicates more light will be absorbed by the plant. Go to the Indoorsunlighting website for further details inc specs and test reports POWER 600W 1000W PRODUCT CODE M2325 M2335 COLOUR TEMP. (?K) 2100 2000 MAX. PPF (µmol/s) 1194 1960 MAX. PPF EFFICACY (µmol/s/w) 1.78 1.80 LIFESPAN HOURS 28,000 24,000 CRI % 30 28 LUMENS 92000 155000