Compact and Portable: This CW key controller is small , making it portable. It doesn't take up much space during use; wherever you can place a radio and key, there's room for this deviceNo Need External Power Source: The device is no need for an external power source and further reducing dependence on desk spaceVersatile Functionality: This controller can also be used as a practice tool supporting vertical manual keys, horizontal paddle keys and semi automatic mechanical keys among others. It supports all forms of automatic keys without compromising any functionalityEasy to Use: The setup is simple; when used as an exerciser, manual electric keys and automatic electric keys only need to be connected to their respective interfaces; when used as a key controller, the automatic key is connected to its corresponding interface while the radio connects to the output/manual key interfaceAudible and Visual Indicators: Whether used as an exerciser or controller not only will the buz sound but also blue LED lights will light up in rhythm providing both auditory and visual cues which are especially helpful for beginners in understanding rhythm patterns<br> Specification:<br> Material: PCB<br> Size Chart:<br> 3.9 cmx2.5 cm/1.54 inchx0.98 inch<br> Package Includes:<br> 1Hand Key OscillatorModule<br> Note:<br> Please allow slightly errors 1-2cm differences due to manual measurement.