For this PH TESTER, it does not includes calibration liquid,the one you get maybe not accurate,In order to ensure the accuracy of this item pls make calibration when you get the parcel 100% BRAND NEW Weight: 65g Size: 15 x 3 x 1.5 cm Excellent meter, very accurate and durable Measuring pH Range: 0.0 - 14.0 pH Resolution: 0.1 pH Accuracy: 0.1 pH (20C), 0.2 pH Operating Temperature: 0 - 50C (32 - 122F) Calibration: manual,1 point This digital pen style pH meter is an ideal instrument for aquarium, fishing industry, swimming pool, school laboratory, food & beverage etc. Please calibrate with the buffer solution before use. 3 x AG 13 button cell batteries (not included ) 1 x pH meter 1 x screw driver 2 pouches of calibration buffer solution (4.0 & 6.86) 1 x instruction manual ( English)