On the right we have a damper rod. The 4 big holes near the bottom control compression and the two small holes near the top control rebound. The oil flows inside the rod and through the holes. The size of the holes and the weight of the fork oil determine the amount of damping.
I change the damping by welding the holes closed and drilling different size holes. I like to adjust the hole size to work with 15 weight oil so you can fine tune the damping with 10 weight for less damping or 20 weight for more damping.
On the left I have added the top out spring at the top of the rod. It cushions the blow when the forks extended all the way. The wide part at the top of the rod can’t pass the bottom of the fork tube. This is what keeps the fork from falling off the end of the tube.
The bolt comes up through the bottom of the fork leg and holds the leg to the damping rod. The spacer fits over the end of the rod and is cone shaped. It uses fork oil to damp out bottoming.