I measured the ER-6i and the Mk5. From the tip of the ear tip to the back of the driver housing it's 1" or maybe 1 1/32" - call it an inch. The Mk5 barrel (with the driver) to the tip end is also an inch. But... the cord fitting at the back (the bit with the strain relief) adds 1/4" to the length between the verticals. It's possible (probable?) that the cord (vs. barrel) end was jammed by helmet padding, levering it off the back of the barrel. I'm guessing at this but looking at a picture of the Mk5 should make this scenario clear.
I don't have my micrometer handy, but a calibrated eyeball check suggests the barrel diameter is about 5/16".
Now to do the road test...
