https://teamknox.com/en/tech/gadgets/labtools/11_pm7/index.html 　It’s a standard pocket tester. I think I’ve been using it for over 20 years now. The phosphor bronze contacts in the battery holder had gotten a little rusty, but once I cleaned them up, it worked again.I tried to replace it entirely with the FNRSI-2D15P, but gave up because the response was too slow, so I use this one when I’m in a pinch. Taking advantage of its compact design, I always bring this along whenever I head out with my tools. Hugo en-us