There were two sized panels included with your order. Regardless of the one you use, the holes for the switches and Start Button are the same size. To attach the Start Button you need to have it in three pieces. The third piece attaches last to the back and has the light and wire hookups on the back but you don't need to worry about that until later. The other two pieces twist apart (like a screw) and once you slide the start button into the hole, you simply screw on the piece behind it to tighten it. The final piece attaches to the very back and locks on. Hope this helps, if you play around with it, it will make sense eventually. If you have any more questions about the set-up let me know. I have the whole thing in my car and it works perfectly. Good luck!