back clip: stable without shifting and without damaging the machine. Condenser Rubber Pad: second response, step faster, without damaging the screen. Does not block the screen: exquisite and small, does not block the map，and two-way design, both left and right are available. Internal hollow design: Don'for t lose the keys when pressing, don'for t the screen, don'for t accidentally for touch the volume keys. Purely physical plug, no need to connect other devices, just install and use.