George Krashos

I apologise for this bit of threadomancy, but I've only now comes across this MOC and think it's fantastic. My problem is that for the life of me, I can't identify the round part that the creator uses for the inside of the "body" next to the wedge piece - you'll know which bit I mean if you check out the pic the author provided of the 'exploded' version. Can anyone give me a hand? I'd love the part ID number. Thanks. -- George Krashos