This was left over after I sold my Beseler enlarger a number of years ago. Found it while cleaning out drawers in the darkroom.
This is a very useful tool for verifying and correcting, if need be, the alignment between the lens board and the printing paper easel. It is essential that the lens board and the easel be absolutely parallel. If you find that one side or corner of your print is always slightly out of focus, the culprit is usually because the lens board and easel are not parallel. This is a quick and easy way to made the necessary correction.
$25 + postage from Canada. Payment through PayPal.
If you have questions, please ask. Thank you for looking.