Here are images of nib units. From top to bottom, a Jowo #6 nib, a Bock 250 (#6) nib, a Bock 380 (#8) nib, and a Jinhao 9019 #8 nib. There are certainly a lot of variations between the nib housings. Somehow, the top three have been getting along with each other pretty well for me.
I was going to measure the TWSBI Swipe’s nib connector, but it’s integrated into the grip section of the pen. My calipers couldn’t reach into the back of the section. I never noticed how the TWSBI Swipe was constructed before.
