Question About Removable Finiales

[sub_bluesy]

I have a couple converter pens that have a removable finial on the pen body. Can anyone explain why the finial can be unscrewed? I cant turn the top of the converter with the finial unscrewed so Im trying to figure out why its removable. Is there a traditional reason why?

[SoulSamurai]

Could the pen body be used for different types of pen? So maybe for ballpoints they use a different type of finial to accommodate the ball point refill? What model and company is the pen?

[jar]

Manufacturing costs.

[mitto]

No clue.

[Mech-for-i]

engineering and production concern. some time more parts not necessarily mean complexity. often in modern day manufacturing it means the opposite; and economy of manufacturing cost also ( single piece barrel require costlier material and working that material ) and as SoulSamurai puts it, it also open up easy way to cater to RB ( which might require a pusher plug ) or BP ( which might require a click mechanism ) using the same barrel parts.