Yep, friction welded so what you see is just flash that AFAIK can easily/safely be removed
Printable View
"closest fit hollow bar"
NB32H
Yeah its got a seam but its cheap and slides over stock arms like hot butter (one the flash from the friction weld is reduced in diameter), splash the MIG around and for probably less than $30 you have arms that most likely wont bend ;)
S
I have some Mecaval 147 hollow bar, 40.5mm OD according to an old post to sleeve mine.
They won't bend :D