special rings 

this ring         OD=45mm, ID=42mm, Thickness=1mm
36cc ring        OD=37mm, ID=34mm, Thickness=1.50mm
43/47cc ring   OD=42mm, ID=38mm, Thickness=1.50mm
49cc ring        OD=46mm, ID=42mm, Thickness=2.0mm
(815-5-2)

from: kstaley20  Well they are the same size that fits a Dolmar 5100s chainsaw.
If that helps