isi 2 roll... Hydrion Chlorine Test Paper provides a simple, reliable, and economical means to measure the concentration of free available chlorine in sanitizing solutions. With color matches at 10-50-100-200ppm, the test paper measures concentrations between 10-200ppm. consisting of a 15-foot roll of test paper and matching color chart, plus 1 additional refill roll. Provides for approximately 2000 tests.