The Horiba Laqua 6261-10C Combination pH / Reference Electrode, for Flat Surface Measurement, Glass Body, # 3014081807 is perfect for measuring samples in shallow containers (e.g., petri dishes) and gelatinous samples (e.g., nutrient agar). The Laqua 6261-10C is ideal for pH measurement of meat, skin, leather, paper, leaves and cloth. The liquid junction of the Horiba Laqua 6261-10C glass-body, refillable pH electrode is located on the flat pH sensing membrane.