Sorry guys,
The only thing that Walter did not put into the box was a set of instructions. He was off to Bangkok for a month and only had a week to make my shocks.
He has just emailed me from Singapore and told me that the Black rubber thingy is the rebound adjuster. These are the first YSS shocks I have ever seen up close and it is an optical illusion when you turn the black rubber thingy the shock looks like it gets longer and when I saw that I went onto the YSS web site and saw that the next shock up had a length adjuster. So, not having any more bullets than that I assumed that is what it was.
This topic was not meant to be a hard core technical posting more a look what happened when I ordered my shocks and the great service I received. I only got the shocks yesterday afternoon and took the pics as I started this topic just so others could get a look at what YSS Z302's look like.
Just so no one is confused about what the black rubber thingy does I will go back and edit the topic involved. I know it will make these threads look odd but It is probably for the best.
Ji