E40 powerstar hqi e 250w 400w d pro halogen metal steam bulb with quartz technology osrampowerstar hqi with quartz technology powerstar hqi e are one sided socket ellipsoidal bulbs with average to high output only permitted for closed lamps maximum permissible outdoor coil temperature 400 c maximum permissible socket edge temperature 250 cadvantages up to 1 000 w output long lifespan good to very good colour reproduction screw socket e40 for simple bulb handling in clear and coate