LISTED IS A MENS 1968 CERTINA DS-2-SuperPh500m-Holy Grail. REF-5801-123. THIS IS THE MOST HISTORICALLY SIGNIFICANT MODEL CERTINA EVER MADE,THIS MODEL WAS USED IN TEKTITE-1 AND TEKTITE-2 EXPERIMENTS THAT NASA CONDUCTED IN 1969 IN PARTNERSHIP WITH OTHER AGENCIES.LOOK UP THE LINK BELOW FOR SOME GREAT DETAIL AND HISTORY OF THE TEKTITE PROJECT https://www.vintagecertinas.ch/en/the-tektite-watch/. COMING TO THIS WATCH- THIS WATCH HAS A SERIAL NUMBER 7144675 THAT DATES TO 1968.I HAVE TRIED TO KEEP IT ALL ORIGINAL. THE WATCH HAS SCRATCHES ALL AROUND THE BODY,CRYSTAL. HAS A VERY CLEAN BEZEL THAT ROTATES BOTH WAYS WHEN YOU PUT SOME PRESSURE(PUSH AND TURN). THE WATCH HAS A 27J CAL 25-561 AUTOMATIC MOVEMENT WHICH IS RUNNING WELL.THE WATCH HAS A ORIGINAL SCREW DOWN CROWN THAT DOES SET TIME PROPERLY.WATCH HAS DATE WINDOW THAT CHANGES EVERY 24 HRS. THE HANDS AND DIAL HAS WEAR DUE TO AGE,PLEASE CHECK THE CLOSEUP PICS TO SEE FOR YOURSELF.THE MARKINGS ARE VISIBLE AND FAIR,THE HANDS SHOW AGEING ESPECIALLY THE HOUR HAND THATS MISSING THE LUME ALTOGETHER,THE MINUTE HAND AND THE SECONDS HAND HAS THE LUME THATS STAINED. WATCH HAS A OLD UNBRANDED RUBBER BAND AND COMES IN A OLD CERTINA BOX THATS IN GOOD SHAPE. THE WATCH MOVEMENT WAS OILED/SERVICED RECENTLY,BUT ONLY ABOUT WORK FUNCTIONALITY. THIS MODEL IS A DIVER MODEL BUT I HAVE NOT ASCERTAINED THE WATERPROOFING AT ALL ON THIS WATCH,THE BACK HAS A GASKET AND SO HAS THE SCREW DOWN CROWN BUT NEITHER HAVE I CHECKED NOR I GUARANTEE SOME OR ANY WATER RESISTANCE.PLEASE KEEP IN MIND. YOU WILL NEED TO HAVE A EXPERIENCED WATCH MAKER DO WHATEVER IS NECESSARY TO CHECK THAT.I HAVE A VIDEO OF IT RUNNING IF NEEDED. LOOK AT PICS AND ASK QUESTIONS,I MAY HAVE MISSED A FEW THINGS IN THE DESCRIPTION. SOLD AS-IS AS DESCRIBED,NO RETURNS DUE TO RARITY. I AM A WATCH LOVER HAVING HAD SOME GREAT WATCHES PASS MY HANDS,THIS IS ONE OF THEM. PLEASE LOOK AT MY LIST OF SATISFIED CUSTOMERS. GOD BLESS ALL.