This is an Air Check Timer, an analog clock and timer for your vintage Yamaha system. Its very old, older than the DT-1, possibly part of one of the first line of units by Yamaha. This one shows sign of age but the clock keeps time accurately. The pins for the other side aer comple and the timer functions hould work, although Ive not sued it. The power outlets work. 100V Japanese market unit. Its one of those very rare pieces - it was sold only domestically - that hardly ever come up for sale anywhere.