Thank you for Itan and Takumi.
I found that thing at my Z. It was a part of Z's damper (see my pic). It costs 10 bucks to get the whole set of the damper but what I need was only the black plastic section, the rod and it's ball. None any LHS at my country sell that things.
Can I know the name of that part and the price at your LHS? I will need some.
Thank you.
TinyRC, u did not read my request, didn't u?
