This size #1L (long) on the left in comparison to the #1 on the right is without texture. Yes they're sold in pairs. If you have out grown the #1 you can move into the #1L or the #2M. The inside diameter is 7/16 of an inch or 11mm. The working length is almost 1 inch. The head on a US dime, nose to the back of the head is 7/16.
Don't know if you ever saw Farrah Fawcett Playboy pictures back in the day (dating myself), but she had pencil-eraser size nipples. Keep these on overnight and you will too. First time I did it overnight I was to embarrassed to go out, even with a bra on. Took about three months of pretty much daily use to get the size I wanted. I can't imagine anyone wanted anything larger than this size, but......
They say to use lip balm as a sealant when you put them on but I found that Vaseline works better and doesn't dry out as quickly as the lip balm so they keep their suction longer and don't fall off.