Type Koopman Chess Clock into a search engine, although you may not find any for sale.
And check out this link: http://www.cln.org/searching_faqs.html
I gave my Jerger (identical to the one you posted) away to a pal in the Phillipines after he mentioned playing in a chess tnmt all wkend to win a whopping $10 after spending more time waiting for a clock to use than actually playing. I replaced it with a Saitek digital chess clock that I don't like (it's a pain to program, definitely user-unfriendly); I shoulda splurged for a Chronos instead.
BTW I checked out some pix of Koopman chess clocks and they are beautiful.
Does anybody collect analog chess clocks? I have recently acquired 2 beautiful Jerger clocks, one in the original box. I am now looking for a Koopman.