Full disclosure: I don't entirely get the point of screen protectors. My screens, from touch-based to desktop, have all survived entirely fine until this moment without them.
The dollar store iPad-specific screen protector comes with an entire page of directions on the obverse of the container. You clean the screen with the provided cloth ("in a dust-free environment"). You then pull back the plastic backing about an inch, align and then press and work your way down the tablet screen.
The cleaning cloth is about 3x3 inches in side, made of a silky material and did a pretty awesome job in cleaning the grime off both my tablet and my glasses -- it's now been tucked into my backpack for further glasses work. So good win on that!
That's where the good
