OK, I located the picture. Go to http://www.texastimers.com then click on Helpful Hints in the links on top of the home page. Scroll down to:
‘Using the MICRO I Timer with the Badge DT Timer in Small Planes”
There are a series of photos showing the timer installation, holes, pull pin, and flag. The flag came from a keychain sold at many airplane gift shops. Lots of airports sell them too.
This flag worked OK at Muncie. At Palm Bay, I went to an actual, full-sized genuine aviation grade “Remove Before Flight” flag. Taller grass at Palm Bay. 🙂