My Focus came with this installed, I think it's called inner housing. On mine there is a little "donut" on each end that I guess is intended to hold it in place. I didn't use any special ferrule as I think the end of the inner housing is recessed enough it doesn't enter into the equation. The ferrule bears on the frame entry hole, not the inner housing.

It was a little fiddly getting the cable from the exit of the inner housing to the exit of the frame. On mine for the FD the inner housing actually extends about an inch out of the frame (at the FD) and is sealed at the exit.

scott s.
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