Check the listing for details. rare Welch Scientific Input Output Wave Current Training Teaching display 66S4. Condition: Used. Listed at 3999.99 USD. This is a vintage item Please see the pictures for condition, completeness, and what is includedWe did not perform any cleaning or restorations and left the item just as foundVery nice color and detailGreat for collectors and displayWell made, great build qualityThank you for looking We purchased these from a former electronics teacher who used these in his classroom. The unit is completely untested, we did not plug it in. We would not even know how to test it or what to look for :). This electronic is vintage, we are making no guarantees on any of the operations. This item may need restoration, repairs, cleaning, tuning, adjustments, or other maintenance. Please do not purchase if you do not have experience with vintage electronics. We would prefer to not deal with extra picky or difficult buyers for this item please. This item is very unique and rare.Thank you for looking.