Omega, Speedmaster Professional, Mark II, movement No. 31001653 Ref. ST 145.014. Made in 1970. Fine, self-winding, water-resistant, tonneau-shaped, stainless steel wristwatch with round button chronograph, registers, tachometer and a stainless steel Omega link bracelet with deployant clasp.
Case two-body, polished and brushed, inclined bezel, hooded lugs, screwed-down case back with Speedmaster logo, flat sapphire crystal with black tachometer scale.
Dial matte black with painted luminous baton indexes, sunk subsidiary dials for the constant seconds, the 12-hour and 30-minute registers, outer minute/seconds and 1/5th seconds divisions. Luminous white baton hands.
Movement. Cal. 861, copper colored, 17 jewels, straight-line lever escapement, monometallic balance, shock absorber, self-compensating flat balance spring, index regulator. Dial, case and movement signed. Diam. 42 x 45 mm. Thickness 15 mm. Approx overall length 185 mm.