Lovibond Checkit ComparatorLovibond Checkit Comparator (Comparator Only) CHECKIT Comparator Test Kits are accurate, easy to use test kits for water analysis. Purchase the appropriate discs and reagents and sample tubes for the tests you wish to carry out. Simply add the reagent to the sample cell, rotate the disc until the color matches the prepared water sample and read the concentration value. Comparator Only We also sell checkit comparators with various combinations of test