FS is a Knight 600A tube tester. It worked the last time I used it with the
type tubes I was checking. To view one just like it click the link below,
This is not the picture of the one I have for sale. Mine looks to be in
better condition than the one listed on Ebay. Questions Email

http://cgi.ebay.com/ws/eBayISAPI.dll...tegory=25 422