Ceiling closed-body speaker with the widest frequency response in its class. This means that only the C series is capable of playing songs for background music without requiring a subwoofer at all. This is thanks to the coaxial design that makes the woofer and tweeter able to produce full range sound in focus. All variants of the C series have been equipped with a secure hook system to ensure that these ceiling speakers do not fall off after being installed, making them safer than ordinary ceiling speakers.