ITS WaterWorks Extended Range pH Test Strips optical Item # Clamping Capacity Spreading Charge Current A 50 Item # Clamping Capacity Spreading Capacity Throat Depth 212 1006 506QCN 6" (15 cm) 7 1 2" 13 3 8" (196 mm 338 mm) 3 1 4" (81 mm) 212 1015 512QCN 12" (30 cm) 7 1 2" 19 1 4" (196 mm 488 mm) 3 1 4" (81 mm) 212 1024 518QCN 18" (45 cm) 7 1 2" 25 1 4" (196 mm 640 mm) 3 1 4" (81 mm) 212 1033 524QCN 24" (60 cm) 7 1 2" 31 1 4" (196 mm 793 mm) 3 1 4" (81 mm) 212 1042 536QCN 36" (91 cm) 7 1 2" 43 1 4" (196 mm 1097 mm) 3 1 4" (81 mm) Specification — ZK2A12K5PL 06 Read against the colour chart on the bottle — no instrument needed Ships worldwide from South Korea by FedEx International Priority Express