one seller told me to order the size of the opening. i just ordered a few from the cousinsuk. they have a good shape selection, but some are available only in even sizes measured in tenths of a millimeter. since some are in uneven sizes i ordered the next smaller. i'll let you know the results. they should be here this week. one interesting thing is that the openings are not round. my digital caliper shows up to 0.8mm differece measuring at different places in the same opening, and it's rare to find one exactly the same everywhere down to a hundredth. tim
