It is an uncertain time for companies across the UK who supply the Armed Forces with flags, belts, medals, swords and sporrans – anything bearing the Queen's cipher.
The cipher is the monogram of a reigning sovereign and consists of the initials of their name and title and often includes a crown.
A change in monarch affects not only the military but also Commonwealth countries right around the world – from Jamaica Defence Force cap badges to Australian Army buttons.
Despite the inevitable death of the Queen, manufacturers cannot really prepare for it. It is something no-one has had to deal with for 70 years.
There are no warehouses stacked with flags bearing the King's cipher, or boxes of pre-made buttons ready to go. The death of a monarch is rather a taboo subject until it happens.
King Charles had not officially announced what his Royal cipher will be. Indeed, he may not even have chosen to use Charles as his regnal name – he could have selected one of his middle names, Philip, Arthur or George.
WATCH: Queen's House at Tower of London rebranded following Her Majesty's passing.
Queen Elizabeth II used a St Edward's crown. Kings historically have used the more rounded Tudor crown.
"If he changes the crown that has an even bigger impact," one manufacturer said.
"The lettering isn't on everything, but the crown is on the buttons of Commonwealth militaries across the globe."
This change is something no one's had to deal with for 70 years.
A tie pin worn by His Majesty at the signing of the official documents proclaiming him King could suggest his new cipher has been chosen and does, indeed, take the Tudor crown.
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So what happens now?
The short answer is – not a lot... for the moment.
Regimental units will likely fly the Queen's colours for years to come. Even if they wanted to replace them – they couldn't do so any time soon.
Each standard takes six months to sew by hand and, from sporrans to swords, there are likely tens of thousands of product lines to change.
There is no problem continuing to bear the regalia of HM Queen Elizabeth II. Postboxes around the UK can still be found with the mark of King George VI and even Queen Victoria.
Some companies have, however, received cancellations from regiments with current orders, now wanting to await the new insignia.
The Queen's House at the Tower of London has been rebranded as the King's House.
While regiments need not clamber to update their uniforms and colours, there is one set of military accoutrements which do need to be replaced, and pretty quickly.
In perhaps as little as six months, King Charles III will be coronated. And for this, all military involved will need to bear his new cipher for sure.