Check the listing for details. EG&G PARC Model 124A Lock-In amplifier w/ Module 116 differential pre-amp. Condition: Used. Listed at 400.00 USD. EG&G PARC Model 124A Lock-In amplifier w/ 116 differential pre amp module installed; This lock in was removed from service & replaced w/ a high end Stanford Research Systems model. At the time it was retired, this unit worked as intended, signal was stable, no noise or jitter evident, no signal degradation evident, & it transferred acquired data via analog computer data acquisition connection. Unit has an Analogic digital display. This is an older legacy electronics unit, & as such it is being sold "as is". When removed from service it was FULLY OPERATIONAL, but- it MUST be understood that it is legacy electronics & thus It is NOT represented to function as a modern, state of the art lock in amplifier. It can be used for confirmatory signal detection/isolation, & as a source for high quality parts & components which might otherwise be extremely difficult or impossible to source. I very much want you to receive what you have purchased in the best possible condition. To this end I will supervise packing & shipping, & I will invoice you for these charges as soon as FedEx picks up the package for shipment to buyer. Unit will be shipped insured & most likely will require a signature upon receipt This is a heavy unit & shipping charges will reflect this. Offered at $400