Viewmasters were popular in California in the late 60s and early 70s. My brother and I had them as kids. They moved into the "toy" marketing in 1966. That probably indicates a date earlier than 1965 when the viewmaster was a stereoscopic slide viewer, not a toy to view Disney cartoons.

Those colors and the style of photography remind me of 1950s-60s Raleigh ads. I have a few since I love the vintage Raleigh roadster 3 speeds.