Eddy Merckx bicycles used by many builders during his career. His natural tendancy of using a builder from his home country saw him come in contact with the Kessel family in the sixties. Kessel became his official builder making most of his Molteni-period bikes until 1971 when Colnago took over. Eddy Merckx also used Masi and Pella during his racing career. Merckx was a fanatic when it came to detail and is often seen measuring and fiddling with position of his bike.
Kessels, father and two sons in Oostende built framework of a very high standard you see in the pictures. They were sold under the brand Main d'Or. Kessels helped also to license the rights to Merck's name to Falcon in England, which paid £ 1 for each decal kit they used for their Merckx bikes. A curiosity: Main d'Or were imported into the U.S. of Western States Imports also sold bicycles under the brand Centurion-Diamondback.
Source: Cykle Hobby