Because it is a roll type, it can be economically used. It is difficult to cut the test paper in the case, and I use scissors. I think it will be better if this improvement is made. In the summer, the sun is hit, it is kept in a place where it gets hot and has experienced decolorization. It is a point that needs attention. I think whether it is convenient that the color code attached to the case is on both sides. Cut it off, put the case, immersed it in reagent, and tried to see the pH at that time, the case was surprisingly opposite, and I felt somewhat inconvenient.