Seiko Dive Watches Terminology
Monster - 'Diver's 200m' written on face, bezel's side profile looks like 'M', luminous indices looks like teeth
Sumo - 'Scuba 200m' written on face, bezel's side profile looks like sumo ring(?), luminous indices are circles except the '12', '3', '6', and '9' position
Tuna - Marinemaster, with a obvious 'shell' resembling a can
Are there other terms that I may have missed out?