This is an extremely rare asymmetric D Shape F300Hz Constellation in 18k solid gold, one of the very few units ever made. 
The overall condition is stunning and very clean, with no damages or scratches, the movement has a new battery and is working properly. 
I have bought it a few years ago from the first owner who brought it to Spain from Venezuela where the watch has been sold in 1973, and this is why has got a rare 18k solid gold south American "D'Agosto" bracelet.
The watch is accompanied by the Omega International Guarantee booklet filled by Salvador Cupello Venezuela (The Caracas Omega Dealer in those times) dated 7th October 1973, instruction manual and fitted with the presentation box (without pillow).