The Seiko 6139-6020 "Pulsations" is a vintage 1970s "doctor's watch" featuring a 40mm stainless steel cushion case, a caliber 6139B automatic movement with 17 jewels and 21,600 bph, and a rotating inner "Base 10" bezel for calculating heart rates . Key fe...
Pulsograph scales are actually quite practical in a sense and generally much more useful in everyday life than tachymeter scales. I have two watches with them, albeit none a Seiko 😊🤷🏻♂️ ...