Philips 4200K Master Color 942 CDM Elite MW 315 Watt, T-12


Superior color quality. Crisp white light. 4200k color temperature, High 92cri, 34,300 initial lumens (109Lm/W). High 90% lumen maintenance at 8,000 hr./High 85% PPF maintenance at 20,000 hr. Unique Open Rated Lamp construction reduces radiant heat from the arc tube and is suitable for open fixture use.


Until the lamp has achieved a least 10 hours of operation, the lamp should never be turned off sooner than 2 minutes, including during the installation test. In case that this has happened, you will have to wait 1 hour before switching on again. Failure to comply with this requirement may lead to ignition problems.

0.8 lbs.
2.2L x 2.2W x 9.0H

What is the importance of color temperature ratings (Kelvin) on bulbs (3000K, 6400K, etc.)?

Kelvin is a unit of measure that rates color temperature of a light source. Lower Kelvin temperatures will display deeper hues of red and orange light. Higher Kelvin temperatures emit deeper concentrations of blue light. As a general rule, one should use

How often should I replace my grow bulbs?

Whether fluorescent, sodium, or halide, we recommend replacing light system lamps (bulbs) every 1 to 1.5 years if operated for a minimum of 12 hours per day. Although lamps older than this might still ignite for multiple years, the quality of light they p

What is the difference between a BT56 and BT37 metal halide lamp?

BT56 and BT37 correlate to the size of the glass envelope surrounding the actual arc tube of the lamp. (Bulb size or diameter (maximum) is expressed as an eighth of an inch for one unit. For instance, a BT56 bulb is 56 eighths of an inch in diameter, or 7

What is a Mogul base(E39) socket?

The Mogul base (E39) socket, has a larger diameter and are primarly used in larger lamp wattages. The designation E39 refers to the diameter of the light bulb screw base in millimeters, e.g. E39 has a diameter of 39mm.

My new bulb isn't lighting up, or only lights up sometimes. How can I fix this problem?

The problem might be a bad connection in the mogul socket. Make sure to disconnect the unit from the power supply, and then look inside the mogul socket for a metal tab. Pry this tab upwards a little bit to make better contact with the bulb base.