Seiko 'Jumbo' chronograph automatic stainless steel gentleman's wristwatch, reference no. 6138-3002, black dial with baton markers, minute markers, day/date apertures, subsidiary thirty minute and hour recording dials at the twelve and six
This was my grandfather's seiko chronograph "Jumbo" [6138-3002]. Still working fine after about 50 years. : r/Seiko