This transistor, shown in the image on the right, was the first mass-produced transistor: manufacture started in 1953. It was a germanium PNP low-power
junction
audio-frequency type at an affordable price, and it opened up the world of semiconductors to the amateur as well as the professional. The oldest examples are black plastic cuboids, with a clearly-visible small glass block in which the lead wires are anchored, as shown next to the ruler. Above that are two later CK722's with a thin aluminium body, filled with plastic. Some had an iridescent blue colour, unique to Raytheon and very characteristic. Many of these transistors were made, and they are still not difficult to find today.
These transistors were originally sold in paper envelopes. There is a market in good quality examples because for many people in the US this was their first transistor and they feel nostalgic about it.
A fellow enthusiast, Jack Ward, has a Web site devoted entirely to the CK722. It contains a lot of images and information, some of it quite surprising, for example the "transistor within a transistor". Have a look!