Cathode-Ray Tube. The display portion of an "old school" (non-LCD) television or computer monitor.
View attachment 4924
http://computer.howstuffworks.com/monitor7.htm
[file]Image:tv-cathode.gif|thumb[/file]
View attachment 4924
http://computer.howstuffworks.com/monitor7.htm
[file]Image:tv-cathode.gif|thumb[/file]