This pH Pal Plus is a change to our previous pH pen of choice as we began to experience a high return rate.  We have returned to the supplier that we used 10 years ago and they are proving popular and more reliable.
 
This easy-to-use PH pen has a clear LCD display giving readings to 0.1 on the pH scale with an accuracy of +/- 2%. The pen features digital auto-calibration which makes it easy to calibrate using Buffer 4 or 7.
 
The ETI pH Pal Plus pen uses three 1.5V batteries (supplied with the pen) to give approximately 2 years of battery life.