Can confirm 1.6mm, keep in mind the slots on these screws are quite wide, so to ensure the driver maintains a good grip and doesn't slide out sideways, or mark the screw slot I would suggest reshaping the driver tip a bit to make it thicker.
If your driver blade is too thin as you apply force to turn the screw you are putting all the load into just 2 small points on the screw, risking marking the screw, it also makes it very easy to slide sideways out of the screw slot.
if you dont have an arkansas stone or similar for screw driver reshaping on hand a piece of fairly fine sandpaper (1200 or so would probably do) put on a piece of glass so you have a nice flat surface would be useful for reshaping.