These pressure gauges, which are one size smaller than the KPA-PA and KPB-PA, are used to measure pore water pressure in soil, sheet piles, piles and boreholes. The KPC-PA is attached to a pile, a diaphragm wall, a sheet pile, etc., and buried in ground to measure pore water pressure. It is also buried singly in ground to measure pore water pressure. The KPDPA is put in a borehole to measure the pore water pressure in bedrock. The feature of these gauges is the dual structure that makes them highly resistant to lateral pressure. Therefore, high-accuracy measurement can be made even if soil pressure changes markedly.