| Answer | Crossword Clue |
|---|---|
| NEON | Filler for a light tube. |
| strobotron | a gas-filled electron tube used esp as a source of bright flashes of light for a stroboscope |
| strobotrons | STROBOTRON, a gas-filled electron tube used esp as a source of bright flashes of light for a stroboscope |
| NEON | Light in a vacuum tube. |
| envelopes | The outer metal or glass housing of a vacuum tube, electric light, etc |
| flashtube | a gas discharge tube that produces very brief intense flashes of light and is used esp in photography |
| flashtubes | FLASHTUBE, a gas discharge tube that produces very brief intense flashes of light and is used esp in photography |
