SEIKO gents wristwatch 'Black Helmet' with chronograph, self winding, Japan 1970′s, reference 6139-7100, stainless steel case including original bracelet, screwed down case back, display of hours, minutes, day, date & chronograph, tachometer graduation, measures approx. 49 x 41 mm, length approx. 19,5 cm, condition 2, property of a collector