Eye Hortilux Metal Ace Conversion Bulb - 400W 

The Hortilux Metal Ace 400 watt conversion lamp is a Metal Halide lamp that operates on a High Pressure Sodium system. 

What's that mean to you? No additional investment in an MH ballast - you can use your existing HPS ballast and still have the optimum blue spectrum energy needed for plant vegatative growth.

Hortilux Metal Ace 400 is completely lead free and has a mogul base. The clear glass bulb will function in both the vertical and horizontal positions and lasts about 20,000 hours of use.

Emits 36,600 lumens. Use the Hortilux Metal Ace 400 in a 400-watt high pressure sodium ballast.

Dimensions: 11.45" Long x 7" Wide

More info from the Manufacturer (PDF format - Lots of detail.)