For industrial tested products:

After manufacture as a standard WGI2xxAx, the part goes through 
additional testing and then "I" is added to the lower-right corner of 
the IC Package. Intel does not re-mark the product code from WGI2xxAx 
to WGI2xxIx, so the I at the bottom right signified the Industrial 
tested product. 

Please contact a Mouser Technical Sales Representative for further
information.

5-0514-31