I know I've seen one of these before but I can't remember where. It's unlisted in the Guide, has no embossing, has a groove across the top, a hole running through it at 90 degrees to the groove, measures 2" X 2", and has a shallow (1/2" deep) rounded tip pinhole. Can anyone tell me what this is and an approx. value if it is more than the $1.50 I paid for it?