If we could choose to buy a 1960-era consumer good (telephone, radio, house, car) that was manufactured using modern manufacturing techniques and modern technology, many of these goods would be significantly cheaper to produce than anything available on the current market, and buying these goods instead of modern goods would result in zero net loss of happiness for the consumer.

A radio, for instance, would look and act exactly like a 1960-era radio, but it could use digital technology, integrated circuits, etc. to make it work. The functionality and appearance of the goods are what remains the same as 1960.