The VM is a new seismic geophone string series usable in marshland. This series is developed independently by Sunfull. The VM series has good water resistance. Its insulation resistance is no less than 200MΩ after being exposed for 48 hours in 6 meters or even deeper water. Because of its compact size, light weight design and low distortion The VM series has an unparalleled advantage to oil exploration in all kinds of shallow water areas.