I use AquaSafe Plus. I don't think it's chlorine... I only put 0-0.5 because the little square MIGHT be slightly off-white, but not significantly, so it falls somewhere between the first 2 colors on the Safe side of the comparison chart.
Nitrites, I'm less sure because the jump from one square to the next goes from "safe" to "caution," and there's barely any visible difference. I might ask my wife to look at the strip because she has more cones in her eyes than I do, but I think that mostly helps with blues. 😄
I'm due for a partial water change this afternoon, which should nudge the nitrites down a bit...