It's very easy to identify the generation of SimplicityTouch that you have.

Gen 4 - Silver color and the S/N begins with ST4.

Gen 3 - Entire frame is black and the buttons are on the left side.
Gen 2 - Buttons are on the right side and it has 2 Wi-Fi antennas on the right side.
Gen 1 - Buttons are on the right side and it has 1 Wi-Fi antenna on the right side.

If you need help with identifying the generation of your SimplicityTouch panel, please submit a support ticket: Click Here