This is a toilet paper spindle to replace your old and dirty current one. You can use the same spring from your old spindle. The spindle is fully adjustable and should work with most toilet paper holders and toilet paper sizes.
After printing, insert the spring into the larger tube. Then insert the smaller tube into the large one and push until you feel resistance. Next turn the smaller tube clockwise and let go when you feel resistance. This will lock the tubes together.
The overhangs inside the larger tube will create strands that need to be removed. I used a screwdriver to just push them out.