Nikon D300 Complete Manual page 234

V1.02
display. Some people are misinterpreting what tempered glass
means, thinking that it is completely scratch resistant or
impervious to damage.
Nikon did switch to a glass covering on the LCD to make it
more resistant to scratching, but that's compared to the older
style acrylic or plastic covers used on some LCDs. Like any
glass, you can still manage to scratch the covering on the
color LCD; it's just more difficult to do with the glass Nikon is
now using.
If you were to sustain impact damage to the color LCD
enough to break the covering, tempered glass will break into
small cubic pieces and not long knife edge shards. Indeed,
any impact strong enough to break the tempered glass cover
will probably shatter the entire cover, requiring replacement.
My recommendation is to keep a cover—either the supplied
BM-8 or a third-party option—over the color LCD at all times
if you can.
The color LCD displays 100% of the picture when viewing
images. If you've turned on automatic rotation of vertical
images, the color LCD rotates those images.
In this book, whenever I refer to the "color LCD," I'm referring
to this display.
Thom Hogan's Complete Guide to the Nikon D300 Page 234