Apparently, the “bold vivid color” of El Marko (or el Marko) markers, made by Flair, were not long lasting enough. The pens have disappeared, though Flair pens survive, made by Newell Rubbermaid’s Paper Mate division.
In 1955, Paper Mate became part of Gillette. The Flair was launched in 1966. Gillette’s Stationary Products Division became part of Newell Rubbermaid in 2000. El Marko was originally a consumer brand of waterproof marker pen sold by the Paper Mate division of Gillette, and was marketed as El Marko by Flair. The original was introduced in the spring of 1968.
No word on when El Marko disappeared.