pH Papers: A series of over 20 different narrow range pH papers, each range covering approximately 1.5 pH units of the complete scale. Permits reading within 0.05 pH. Packaged 200 identical range test strips per box. Also available, DUO-TEST ROLL - FC111 (pH range 1 to 12) Packaged in 5 meter rolls in a specially designed plastic self-dispenser.