Seiko PROSPEX PADI Automatic Diver’s watch with a stainless steel case. To celebrate the partnership with the Professional Association of Diving Instructors, SEIKO has launched a special PROSPEX PADI edition this year. This PROSPEX PADI Special Edition operates with the Automatic 4R36 calibre and is a re-edition of the Seiko Pepsi 6309 model from the 1970s, featuring the same 45 mm diameter stainless steel case shape. It features a bright blue dial with the PADI logo and a unidirectional rotating stainless steel bezel with blue and red carbon titanium coating, echoing the PADI colours.