This is a pair of rare original production LilFreQ units (silver/chrome knob version) with sequential serial numbers. Although this seems to be the preferred version, the power supplies were known to be an inferior design so I just had these units serviced by Empirical Labs. They upgraded the power supplies, chassis, power switches and AC inlets as well as recalibration restoring them to factory spec. Best of both worlds. One unit has some minor rack wear on the top which is not visible when racked, they are otherwise very clean.