The Government had brought in the concept of TDS, through which persons are required to deduct TDS and deposit the same with the Government. Know more about TDS on fees for professional and technical services here
There are some tests, such as Salt, Total Dissolved Solids (TDS) and Oxidation-Reduction Potential (ORP) that can't be done with any of the above testers. That's where a PockeTester comes into its own. Dip-n-Read convenience.