The kit comes with a 5th Gen magnetic screen protector which needs to be installed on the camera LCD screen before use the LCD viewfinder. The LCD viewfinder then can be attached or detached from the glass screen protector as needed, instantly.
Please see instructions for detailed steps in installation and make sure to get familiar with how to open and close the viewer.
The #S1 model is suitable for:
Sony A7 II, A7 III, A9, RX100 I-V, RX1 series, RX10 series