Came up with these as the correct size to replace the o-rings on the swagelok quick connects(3/8 and 1/2"). Verify for your application
1/2" QC rebuild
fkm oring 14x1.78
fkm oring 12.42x1.78 - highest wear
fkm oring 9.25x1.78
3/8" QC rebuild
fkm oring 10.82x1.78
fkm oring 9.25x1.78 - highest wear
fkm oring 6.07x1.78