Taylor M-6555 Myron L ULTRAPEN™ PT1 Conductivity/SalinityTDS/Temperature Meter. When accuracy, speed, and reliability are crucial to your operations, you can depend on the performance of Taylor’s water-testing instruments. Having the right tools for the job can make all the difference in the world, especially when it comes to monitoring water quality. This PT1 is easy to use. Push the appropriate button to measure, then dip the ULTRAPEN in the water.