1. The BASE holds the pins which connects to the electrical circuit and supports the lamp in the lamp holder.
  2. LEAD-IN WIRES connect to the base pins carrying the current to and from the cathodes and the mercury arc.
  3. The EXHAUST TUBE is where air is exhausted out through the tube during manufacture and inert gas is introduced into the bulb.
  4. The glass STEM PRESS provides an air tight seal for the lead-in wires which assures the same coefficient of expansion as the glass.
  5. The HOT CATHODE at each end of the lamp is usually made of coiled-coil or single-coil tungsten wire and is coated with materials which emit electrons.
  6. The inside of the bulb is PHOSPHOR coated. This coating transforms ultraviolet radiation into usable light energy for your plants. The color of light produced depends on the composition of the phosphor.
  7. The GAS within the bulb is usually argon or a mixture of inert gases at low pressure. Krypton is sometimes used.
  8. A MERCURY ATOM from a minute amount of liquid mercury is placed within the bulb.
  9. The BULB which is usually a straight gas tube.