This Low Range DPD Testing Starter Kit includes .75 oz reagents and is for use with Taylor 2000 Series comparators. It tests for free and total chorine, total bromine and pH. Easy to follow instructions allow for hassle free testing. Taylor formulates its reagents to remain effective for at least one year, with only very few exceptions (molybdenum indicator in liquid form is one; after four months old it should be tested against a standard periodically). As a general precaution, replace all reagents more than one year old, or at the beginning of a new testing season.