The INTEGRA III SYSTEM Audio Mixer modules are designed for professional audio applications. These units are intended for high reliability, 24/7 installations. There are eight audio mixer modules. Choices to be made are microphone input level (4 models), or line level input (4 models), and number of inputs (2 to 5 per module). The gain adjusting trimpots are mounted on the backplane assembly. Trimpots mounted on the backplane allow the gain adjustments to remain set, even when a spare unit is put into service. Models with 2 to 4 inputs may be linked. The link feature allows the units to be connected together to provide additional inputs to one output section.