The Oakton WD3585008 pH Test Paper, 0 to 13 pH (Indicator Roll) features a 1.0 pH unit interval across the entire range. Packed in a plastic dispenser with an extra-large color comparator chart, this test paper features vivid and easily distinguishable colors to provide an instant result. This paper roll measures 1/2 in. wide x 50-ft long (1.3 cm x 15.2 m), enough for approximately 150 tests.