atc 70 piston??

[Bielz81]

Hi im trying to figure out what size piston is in my atc 70, i got the nubers 937 off the side of it, any help would be greatly aprreciated.

[atc500x]

937 is the model number,designated for the atc70.Std piston have no mark on top,oversize is stamped,0.25 , 0.50, 0.75 , 1.00....

[Bielz81]

thanks alot, i didnt see anything on the top