OMEGA "SPEEDMASTER PROFESSIONAL MARK II Steel chronograph watch, black 3-counter dial with painted baton hour markers, bezel with tachymeter scale. Screw-down caseback. Hand-wound mechanical movement, signed and numbered 31001789. Steel bracelet, articulated links with adjustable steel folding clasp, signed. Circa 1970 (scratches, service bracelet). Diameter: 41.5 mm.