SON-T tubular lamps are gas discharge lamps that use sodium to produce light via wavelengths. They are often used in industrial lighting and are one of the oldest types of gas discharge lamp there is. The way to tell if it has an internal ignitor is to look at the small triangle which should be etched onto the lamp itself. It will have the letter “I” in it if it has an internal ignitor. If there is no lamp in the luminaire currently, look at the gear tray and see if there is an ignitor wired into the circuit. In traditional lighting magnetic ballast circuits, you should have a ballast, capacitor and ignitor. If no ignitor is present in your circuit, you need a lamp with an internal ignitor.