Every MAC product comes with a 3-digit code which is written on both the actual product and the box it comes in.
The last digit is always a number (0-9) and it indicates the year this very product was created. For example, if it’s 9 it was created in 2009 (or 1999, but you would know if it’s over ten years old). If it’s 2 it was created in 2012 or 2002, but you could tell if it’s brand new or ten years old product.
The second digit indicates the month it was created. So numbers 1 to 9 are months January to September (1 for January, 2 for February… 9 for September). The next months are indicated by the letters A, B, C. So A is for October, B for November, C for December. Hence the second digit can be any number from 1 to 9 or any letter from A to C.
The first digit is always a letter and signifies the production run that month A was the first run/ batch, B the second and so on.
So an A41 product was made of first batch in April 2011. A BC9 item, was made of second batch in December 2009. …