PH Paper

Main asset: its price. A large amount of tests for cheap.
The color table is provided with bands (brown, yellow, green, purple, all 14 shades corresponding to pH values)
Test with vinegar (acid): Scarlet result. Problem does not match any color swatch. Very different brown shades of acid pH.
Test tap water with another tester pH 7. Results with this test 8-9
Test with a base (Marseille soap suds). Result 8-9 same color as tap water while another tester gives 10.
The various test make me doubt the reliability of these strips.

Finally when you realize these tests, the fingers are yellow with the product, even if the strip was not fully wet. Just knowing and not put his fingers in direct contact.

Even if the boxes are not expensive, the problem is reliability. Where an assessment to 2 stars.