Thread is matched to your ball color at no charge.
For example, if you order a Green/Black ball, the thread will be Green or Black, but usually Green.
The reason might be that you order 5 black ballz and 2 ballz Green/Black... black will stay in the machine and sew the whole set.
This thread option is for every thread change on your order... if you want a different color thread on every ball, the charge is $5 every time I have to change the thread.
If you get 5 orange ballz and 5 white ballz, there is no charge for the 2 different threads, however, if you want orange on the orange ballz and also the white ballz, that is off of the standard procedure and will cost $5... Often 2 different people are producing your ballz.