These are flex material printed 8MM rod mounts. they assist is helping to dampening the noise of the Y bed movement on most i3 type printers with a 2020 frame setup as well as possibly on other frames with 2020 extrusions.
Obviously the yellow is flex and the red (clamp) are PLA or what ever you choose
It does help, but it's not the end all to noise. But they do lower the amount of vibrations transferred through to the frame while not adding slop to the carriage or it's movement.