Hanna Instruments
Hanna Instruments makes a wide variety of pH meters or meters and underwater testing equipment for home drinking water, aquarium use, and in the laboratory.
If you're looking for good hand held pH meters or other drinking water testing products such as combination testers and one of the good quality analytical products then check out the Hanna line.  These fit hand and hand with our mini Demo Ionizers we offer.

HANNA Instruments HI 98121 Waterproof pH-ORP-mV

Not near as popular as the MW500 ORP meter a study seller in the ionized water community.  The Hanna instruments HI 98121 multi function portable pH and ORP meter can simultaneously do multiple measurements to measure negative oxygen reduction potential.