The Myron L DS TDS Meter model 512T5 is a portable, hand-held single-range instrument with a scale of 0-5000 ppm. Single Range DS meter. Quickly determines the ppm/Total Dissolved Solids of almost any solution. Field-tested design has evolved over 40 years, making this the most popular and reliable hand-held conductivity meter style in the world. Fast, accurate, on-the-spot measurement with built-in electrodes for maximum protection.