Metal Halide bulbs are a member of the High Intensity Discharge (HID) family of lighting products. Metal Halide bulbs are among the most energy efficient sources of white light available today. The latest breakthrough in the field of metal halide technology, Philips MasterColor Ceramic Metal Halide lamps provide unparalleled uniformity and consistency in lamp-to-lamp color - both initial and throughout life - as well as higher efficacy  than any other low-wattage metal halide bulbs available.  The secret to Philips MasterColor Ceramic lamps unequalled performance is its ceramic discharge tube, which combines the white light and high efficacy of metal halide lamps with the color stability and reliable, long life of Polycrystalline Alumina (PCA) technology.

Philips MHC50/U/M/4K ELITE (42992) - 50W Metal Halide, Universal Burn Lamps are intended for use in enclosed luminaires. Philips ALTO light bulbs have little or no lead in their glass or bases, and are produced with little or no mercury.

Many of these products also offer additional features such as energy efficiency and long life, and are packaged using recycled and/or recyclable materials. Philips Ceramic Metal Halide lamps that are designated as ALTO pass the U.S. EPA's Toxic Characteristic Leaching Procedure (TCLP) test for hazardous waste determination.

Initial Lumens 3,750, Mean Lumens 2,550 and a rated average life of 20,000 Hours.  The color temperature of the MHC50/U/M/4K ELITE bulb is 4000 Kelvin (K) and has a Color Rendering Index (CRI) of 92.  The bulb functions on an ANSI Type M148/M110/E. These Philips ALTO Metal Halide Lamps employ an E26 medium base and are designed with a narrow neck ED17 bulb.