I have a projector screen which weighs about 8 kg (~17.6 lbs) and to light it up a little for when I don't use it I decided to mount a LED strip behind it. I already bought matching strips of wood (24 mm / ~0.9 inches). The screw head has to leave a space of about 2 mm (~1/10 inch) so that I can hook the projector screen.
The wall is no drywall, I suppose it is out of concrete or bricks. I've only put nails in it and I think I won't get them out if I have to...
The projector screen frame has two mounting holes in both top corners.
Which length and diameter should the screws have? Maximum diameter of the mounting holes is 11 mm (~0.4 inches)