MBO, a popular German electronics manufacturer, produced a large serie of pong systems named "tele-ball" with numbers ranging from 1 to 9. Though they had some cosmetic differences, all these systems were very close to each other in terms of functionality.
The Tele-Ball is the most basic system of the whole range, offering only the 4 classic pong games in black & white.
The two big silver dials on the front panel are used to switch the system on/off and to select games.
The Tele-Ball IV is the colour version of the original Tele-Ball, with the four same games in colour. It even uses the same plastic case with minor differences.