Folks, I checked-up a few more shops and can confirm that currently there is NO ‘tempered glass screen protector’ in the market that is actually customised for the Note 4. I am talking about all the items (various brands) that are labelled as ‘for SAM Note4, 0.26 mm).
All the brands (premium or cheapo china-make or lobang) create a very noticeable 2-3 mm gap in the borders of the screen. Apparently this is because of the unique surface features of the note 4 screen. Over time, I guess the exposed adhesive underneath will attract a lot of dust and small particles. Regretfully, I was told that even a glass or PET screen protector will leave a 3-4mm gap at all the sides, all over the screen!
Not sure if it is a manufacturing/design fault (screen gate?) but the glass screen appears to suddenly taper off/curve down by 0.5 mm or less, all round the 4 sides before the tiny gap that joins the metal frame.
The air bubbles elsewhere, are more to do with the quality of the screen protector.