Glad this posting was started. Just bought some Kenmore bobbins last week and this is so funny because I was passing through the store and saw the sewing department.
Being curious I took a quick browse. They had clear bobbins but there was no "class" identified on the package front or back. Previously, in buying clear bobbins I had to note that they are not the same. One type has a curved surface and the other type is flat. They are not inter-changeable. Ask me how I know.
Took them home and [at least for me] these flat ones fit my Janome.
Yipee, a package is half the cost of the others from the local sewing/repair shop.
Hush, let us not tell or the price will be raised. :-)