Direct reading, accurate and rugged meter for testing soil acidity (pH) and soil moisture content (% relative saturation). The Kelway tester operates on the principle of electrical potential between two dissimilar metal plates - without batteries or any external power source. When inserted into moist soil the HB-2 registers degree of acidity on the upper scale. The lower scale shows degree of moisture (% saturation) when the switch button is held depressed. Size: 16cmx5cmx5xm , weight 150g. Includes carry case and instructions.. High quality professional unit, made in Japan.