This 2IN1 Two TF cards commutator is specially designed for Raspberry pi B+/2B/3B with double switch systems. You could enjoy the convenience of using two TF cards at the same time to transfer to different systems for playing at the poking of the switch. Moreover if you could change the dial switch to arduino or SCM GPIO controlled, it could help you realize wireless/ remote/ infrared remote control system etc. Note: It should be used when off power or its system will be damaged when on power to switch.