Bluelab Cal Sol'n Ph 4.0 236ml

Excellent product to ph your meter; is needed if you have a blue lab ph pen and lasts a long time. However, compared to other solutions, this is on the expensive side. I will purchase again in the future since I have the bluelab ph pen and I like to use the right products to match the pen

very misleading photo, this is only the 4.0 reference buffer....why not just use an accurate photo?

What can I say? It successfully calibrated my Bluelab PH pen. It works as it should.

Sealed perfectly works perfectly

Can't go wrong with bluelab.

Works great, would buy again

This should be 13 dollars

Serve the purpose

very satisfied

works well