The last ones I ordered came from a fairly local company but after some looking into and research I found that the ones they had were the WaterProof ones and they did not work like the first ones we got or did they look the same. I pretty well trust them and am not sure about the shelf life. I put them under the print side of the shirt, I want the bottom side of the inks temp. You can buy a bunch of them for the price of a doughnut probe and I have heard people complain about them also.