The card contains a method of signing onto the internet, registering and using a card to get 20% off purchases.
Many people (me) will not take advantage of this so the company has wasted their money on paper and postage.
Since I do not know the process of marketing, this may be a very good idea for hiking sales.
IMHO, it would be much simpler just to lower prices in the store without all the in-between steps to that goal. Perhaps I have a bad attitude but when I tried to go online to retrieve the method for getting a $3.00 rebate for ink cartridges, the darn thing wouldn't process. I just took the cartridges in to the store and asked them to please recycle and forget the rebate. The clerk appeared shocked, probably thinking that any idiot ought to be able to navigate the instructions.
So with that experience, I decided to not even try the 20% deal which arrived a day or two later. After all, it's only money.