The LDEO standard seismometer design has been in use for nearly 10 years. The LDEO lab has built and operates 30 standard OBSs as part of the NSF OBS instrument pool. The seismometer sensor is a L4C 1 Hz geophone, with a low-noise amplifier, giving useful response down to 100 s, and a differential pressure gauge. This instrument has been used in both year-long passive-source and shorter-term active-source experiments. The design includes dual redundancy with two transponders and two dropweights.