I figured some of yall may know what these are for. I know it will measure vacuum and PSI, but what would/could it be used for? I have literally about 300 of these things, they are new (many in the box) but have around a while and dusty. I was planning to ebay them if they are worth selling..

- like you said, mine is the same one.... not sure what else I'd use it for. Tire pressure for the PSI maybe?