Bests & Worsts Reviews from Amazon

They work for me. I don't have anything to compare them to, so I don't know how accurate they are, but these give me a ballpark idea of what my tank parameters are like. Overall I'm pleased with them. The only annoying thing is the color chart is inside the label not printed on the bottle. I've attached a photo, since it would be very easy for the chart to get ripped off and lost.