Every Seen One of These...?

Have you ever seen one of these...?

I found this in a 1993 Silver Proof £5 coin commemorating the 40th Anniversary of the Coronation of QEII from The Royal Mint (UK).
(It is c.1.5 inch square).

The Coin was also accompanied by a COA all in a burgundy 3.5 inch box as one would expect...

Keep safe & well ;-)

Wow, no, that is odd and unusual. 

You normally see a returns notice on the payment slip, but nothing like this. 

This might be something special. Hold onto it !!!!

Nope I have never seen 1 of those before