Short-PeriodUltra Low NoiseBorehole Seismometer,ModelGS-13BHThis is a borehole version of the

Model GS-13 seismometer, having a normalized generator constant of 2,000 V/(m/sec). It can be installed in boreholes up to 300 m deep, in any given inner diameter between 102.6 and 200 mm.

Short-PeriodUltra Low NoiseBorehole Seismometer,Model GS-21This is a borehole version of the

Model GS-13 seismometer, having a generator constant of 458 V/(m/sec). It can be installed in boreholes up to 300 m deep, in any given inner diameter between 102.6 and 200 mm.

Short-Period Borehole Seismometer, Model 20171

This is a borehole version of the S-13 seismometer, having a generator constant of 650 V/(m/sec). It can be installed in boreholes up to 300 m deep, in any given inner diameter between 102.6 and 200 mm.