How oversized are these oversized pistons???

Hi Guys,
 
I have a bit of a problem, and im sure for someone it will be an easy question. Im not quite sure how to read the information on the top of piston in order to identify how "oversized" they are.
 
I have two configurations to choose from.
 
One:
On the top of the piston it has "Top .04 WI", and also has "RA2526 0.75"

 
Two:
On the top of the second piston it has "Top .04 FG" and then a bunch of number i can read and "1.00" (again see below)

 
Can someone tell me what size oversized these pistons are?. I thought the .040 was an indicator, but then when i measure both pots with a vernier, they seem to be different at a rough measurement.....as was the bore size of each. So then i started thinking maybe the .75, and 1.00 respectively had some impact. These pistons are out of different motors.
 
Can someone help?
 
Cheers
 
Dave

Thanks very much James.
 
Seems so obvious when its put in front of you.
 
Dave