Good question RR.
The green kind. RCBS. I verified it against a couple of other scales and with known weights when I first got it. I always zero it out before a session.
Every once in a while I use it to weigh bullets and it's never given me reason for concern about mis-reading. In fact, I'm usually impressed with how accurate it has been. It has been so sensitive, I had to build a wind box for it so I could use it at the range.
I also have it mounted "high" so there's no optical error.
But thanks for asking, that's a darn good question.
