Maintenance Engineering's premium quality metal halide lamps are guaranteed to last 50 months. M.E. MH lamps have pyrex envelopes, which are designed to resist thermal shock. Special fill gases are a unique blend of Sodium, Scandium, Thorium Iodide, Mercury, and Argon. The precision blending results in better lumen maintenance and minimal color shift. Quartz arc tubes are manufactured to withstand the high pressures and temperatures of operation, and their ceramic ends are designed to control temperature. Helical electrodes and bi-metal starting switches optimize starting and extend lamp life. Nickel plated steel supports are mounted inside to resist shock and vibration which helps extend lamp life. A Nickel/Brass base is used to create a positive electrical contact, while resisting corrosion and freezing in the socket. All these features make it easy to see why Maintenance Engineerings metal halide lamps are guaranteed for 50 months.