Bluelab PPM Conductivity Pen

The Bluelab PPM Pen is the most ergonomic and easy to use PPM pen available for hydroponics and indoor gardening. The Bluelab PPM Pen is completely waterproof, so you don't have to worry about accidentally dropping it in your solution. The Bluelab PPM Pen also has one button push calibration. No more hard to follow instructions to make sure your PPM meter is accurate.