On many small bikes and ATVs you see too much of your shoulders and arms in the mirrors. These move the mirrors 6.5cm out, and slightly up, allowing for better rear view.
NOTE: Each side requires two M8 hex nuts, one to stop the threading in to the handle bars at your chosen point, and one to hold the mirror in at the other end. Most mirrors come with one on the threads already. Use that one above and the new one below.
Available on Amazon: https://www.amazon.com/s?k=M8+hex+nuts
Or your local hardware store likely has them.
This if for mirrors with 8mm aka M8 threads; 10mm is more common, check your size. Printing this at 125% would make it 10mm, though the threads might not match.
My test print in PLA snapped off the first time I tried to thread it in. My later one in ABS works fine. So either maybe use 100% infill with your PLA or use ABS. It will be a lot stronger.