HEUER. A STAINLESS STEEL QUARTZ DIVERS CALENDAR WRISTWATCH. Model: 200m Professional. Reference: 980.006. Date: c.1980. Movement: Cal.536 121. Dial: Original black dial, luminous markers and hands, date aperture at the 3 o'clock position. Case: Large case, uni-directional rotating bezel, crown guards and screw down back numbered '6130 W20' & '980.006' outside and signed 'Heuer Leonidas' inside. Strap: Later black leather with steel pin buckle. Signed: Dial, movement, case. Size: 44mm including crown.