Ohaus pen meters provide accurate measurement of pH, oxidation-reduction potential (ORP), conductivity, salinity and total dissolved solids (TDS). Starter pen meters are the economical option when you are simply looking for meters that will provide accurate measurement with no restriction. Each meter offers simple operation in a slim & portable design providing fast, straight-forward results time and time again. Durably constructed to withstand wear and tear, Ohaus pen meters provide a sturdy plastic, waterproof housing, protective safety cap, integrated wrist strap and auto shutdown feature to preserve battery life.