This Aeroflow Performance viton 9" Ford pinion seal are good to over 200 degree Celsius. The stock rubber seal starts to deteriorate at about 120 degree Celsius making this a great upgrade when building a diff. Outside Diameter is 3" ( 76.20mm ). Inside Diameter is 1.813" ( 46.05mm ). Overall Thickness is 0.5" ( 12.70 mm ).