Wrong sizes I think, but I like the direction. ID, OD, CS appear to be the standard measurements. Seems an odd choice, as if you’ve got two the third derives. There’s likely some sort of reason. I measured CS and OD. 1mm CS is a standard and .5mm CS is a standard. .8mm doesn’t seem to be though. A 1mm o-ring that got stretched hard, maybe. Or they’re not made of silicone in the first place. Argh. They’ve had a day to relax. I’ll measure em again and see if it changes. Bottom on I doubt will move. Top one might though.