The 311-8529 Dell projector lamp replacement comes with a genuine original 165 watt Osram P-VIP bulb inside.  This lamp is rated at 2,000 lumens (brightness equal to the original Dell lamp).  The 311-8529 lamp has a rated life of 3,000 hours (5,000 hours in Eco mode).  Beware of cheaper lamps made with generic bulbs that have lower light output and reduced lamp life.