Reference Electrodes are made of Copper Sulfate, Silver Chloride and Antimony, which used as a half cell to build an electrochemical cell.
Portable Electrode usually has a light weight which increases flexibility while at the same time maintaining quality performance and portability, easy to load and carry. Permanent Electrode
Permanent Electrodes are designed for 40 years life, but it usually lasted for 20 years according to the engineering practices.
The permanent electrode applicant to bury in soil, and we recommend Ag/AgCl electrodes to be used in chloride ion contaminated soil.