Ammonia concentration of ammonia refractometer RHA502 ammonia concentration meter, you can quickly measure the concentration of ammonia. Measuring range 0-40%, simple to use, you only need a few drops of ammonia to the lens, you can immediately see that the concentration of ammonia. Product name and model: RHA502 ammonia concentration measuring range: 0-40%, the smallest scale: 0.2% Dimensions: 27 * 40 * 160mm with automatic temperature compensation 0 ~ 30 ℃ Packing List: 1, a 2 refractometer, a manual 3 screwdriver a 4, a 5 straw, glasses cloth a six, a dedicated box Tianyuan Xin Branch optical instruments, hand-held refractometer factory direct products, a lot of cash, fast delivery, after-sales guarantee, you are welcome to visit and cooperation!