Sunleaves pH Test Kit 

The Sunleaves pH Test Kit gives hydroponic gardeners a simple, foolproof method of getting fast, accurate pH readings. 

The pH indication solution is highly concentrated and requires only one drop per test.

There's an easy-to-read, waterproof color chart on the side of the solution bottle.

Sunleaves pH Test Kit comes with a quality test tube and measures pH levels on a scale from 4.0 to 8.0 pH.

The 30 ml bottle provides over 800 tests and has a long shelf life.

More info from the Manufacturer (PDF format - Lots of detail.)