A 3 volt glow coil was used as an ignition device on the Astral Frigiking brand of refrigerators. Some RV furnaces of that time period (mid seventies) also used glow coils for pilot ignition, but they were 12 volt.
To operate the glow coil, the user pushed a black ignition button which did two things: it opened a gas valve allowing propane to pass through the glow coil, and also activated a switch which supplied electricity to the glow coil. The resistive windings in the glow coil (about 1.75 ohms) caused the glow coil to become red hot and to eventually ignite the propane passing through it. The user also pushed a red safety valve button at the same time as pushing the ignition button, allowing gas to flow to the main burner. The flame of the glow coil ignited the propane leaving the main burner. After the main burner was lit and the safety device engaged, the user released the ignition button and the glow coil flame went out.
In theory, the glow coil seems like a pretty nifty device, but in reality it had its problems. Voltage to the glow coil was supplied by two "D" cell (flashlight) batteries in series. The batteries didn't last very long and, just like an old flashlight, the battery compartment had a tendency to become corroded, loosing its connections. Also, at today's point in time, the ceramic piece connecting the glow coil body to its gas line has invariably been broken for one reason or another, creating a gas leak.
The glow coil is no longer available and would not be a good investment if it were. The refrigerator can be lit with a match, but requires two people. One person has to be inside pushing the red safety valve button (don't push the black ignition button), while a second person is outside at the back of the refrigerator holding a match to the burner. A "handy" type person can create a piezo or electronic igniter system to replace the glow coil.