Review on Extech PH105 ExStik Electrode Module by John May

If they work, they're great. Unfortunately I bought 4 of these for our joint business because my co-workers keep dropping our PH meters. The first worked, the second worked, then we got to the third and bam, not good. Grabbed the fourth, not good again. The return period had expired so I couldn't return it. It does not involve any extra costs. Get what you need and make sure it's good right out of the box.