A discount on on stamps at the Post Office.
A pensioner concession is stamp is 60c, instead of $1.
You can receive up to 50 stamps a year - that’s a total saving of $20 - if you use that many stamps.
Because they are concession stamps, they are not “priority” mail - that will cost another 50c.
How to apply?
You need to apply for a MyPost concession card via an application form available on the Australia Post website.
Having a MyPost card may have other benefits - however all the work for a a discount of $20 (provided you use 50 stamps a year) may not be worth the effort!