I used this kind of timing light in the '70s and '80s for my VW Beetle and Chevy Nova. It is filled with neon gas and glowed an orange light when activated. I dunno if the Xenon light mentioned above was a brand name for this thing, but it's definitely a misnormer. Real xenon light source has a bluish white light. That said, the orange light of this timing light as above was weak, and I could only use it when it was almost twilight or night, LOL. I had to mark the timing marks with white chalk, Liquid Paper, or white paint to see them clearly. But it was simple, practically indestructible (unless you dropped it and shattered the glass) and cost was unbeatable. Now, if only I can find my old unit in the old shop .....