The reverse was designed by Dennis R. Williams, those are his initials.
these nuts
Air Raid Precautions
The initials K.R are the best.
Blitz in WW2 was an intensive campaign of aerial bombing.
RCEME = Royal Canadian Electrical and Mechanical Engineers
AT
The initials SWL mean Safe Working Load
These are the designers initials.
I saw Mummy Kissing Santa Claus - Drove me nuts
Millimolar
KC is the initials of his FaceBook account, apparently.
tgat
Initials of the maker.
Makers initials
If you mean initials, then they are HI.
I hope you mean 'What do the initials 'UN' mean - United Nations.