Put the knob on the M4 screw.

Start twisting the M4 screw into the one-way ring.

Press the M4 nut into the hex-shaped hole on the inside of the one-way ring. If the fit is too tight try turning the screw until the nut is pulled into the hole.

It is important that the nut and the tip of the screw be flush with the plastic for the next assembly step.