The TR-63 was introduced in 1957 - it was the first "pocket-sized" transistor radio ever made and the first Sony-branded product exported to North America, by the then-named Tokyo Tsushin Kogyo company (Tokyo Telecommuncations Engineering Corporation). It became a huge commercial success, over 100,000 units were sold.
It seems "pocket-sized" was a bit of a marketing gimmick at the time - although smaller than any competing product, the TR-63 was a bit too big to fit into a standard shirt pocket. So story has it that company salesmen wore custom-made shirts with slightly bigger pockets to show off the TR-63's small size. But unlike desktop radios of the day which were promoted under the idea of "a radio in every home", the TR-63 was uniquely marketed as something each person could own and carry with them. A foreshadowing of the Walkman and iPod, perhaps?
The TR-63 contains a whopping 6 transistors. By comparison, the Cell processor chip in the PS3 contains two to three hundred million transistors. That's an indication of the progress made in the electronics industry in the past 50 years.
In Japan the TR-63 sold for 13,800 yen, and the original export price was U$39.95. It was available in 4 colours (yellow, red, green and black).