It's a screw driver to mount Hexagonal screwdriver head.
There is a space in the interior for storing the screw head, the long and short.
I suggest to not mount and dismount heads too often, it's only plastic :), it's better to mount a adaptator head. I have made it in ABS.

Hexagone size is 7mm inside.

there is 2 version the smaller is 20mm large and the larger is 25mm large (XL parts), depend of your hands.

Print 1 of each or the plate then use 3x M3 20 or 25mm long + nuts
the cover is just held by the 2 sides.