JED is a long-standing pioneer in water chemistry and maintenance products. These Jed 5 factor test kit refills reagents will let you know what your eyes can't see and determine the water chemistry. Whether you need to apply chlorine or reapply other reagents to balance it out, is actively determined by these 5 factor refills that can be used with the test kit. It calculates factors like pH levels, alkalinity, hardness and acid demand. The pack comes with clear instructions and number of drops that need to be used to carry out the test.