Marks on the case chronofighter oversize watches have been designed especially for the needs of professional divers they are rugged and easy to read the chronofighter oversize diver deep black watch comes with g1734 automatic bi compax chronograph calibre it makes 28 800 vibrations per hour the timepiece comes with incabloc shock absorber 27 jewels and a 48 hour power reserve the chronograph has its seconds and 30 minutes counter a helium escape valve is available as well the watchs d