The Suzuki SPL-10 Piano Lab Teaching System puts you in charge by allowing easy monitoring and communication with every student in your keyboard class. The verbal switching network allows 2-way communication and lets you monitor the progress of up to 10 students at a time. You can combine up to 3 systems for classes of up to 30 students! Performance can be monitored on an individual basis or classes can be split into 2 groups based on lessons learned. It is the most affordable product available today, with everything you need to set up a lab. The Suzuki teacher's unit has a fixed AC cord.