The threaded rod is used to connect clevis to the yellow part. It just screws into the plastic, then the clevis screws onto the other end of the rod. It comes in the package. I later found that I needed more of them so I bought some 2-56 all thread, and cut off what I needed.
The yellow part is what transfers the motion. The red tube is just a guide path and needs to be secured at both ends, and if it is really long, maybe in the middle as well. Without the red part, the yellow part is like "pushing a rope". Doesn't work.
This is what you get in the package. The black thing is a piece of rubber tube, that I cut into small sections and use as stops. The little clips are used to hold the clevis closed. I don't usually bother with those.
