ZBrushCentral

Zspheres cool way to create knuckles...how did they do this?

Hi,
So I opened up Zbrush’s project "Zspheres/ DRAGON " and I noticed a cool way to make knuckles. If you open the file and drag out one of the fingers (see image) it will automatically create a nice enlarged zsphere when you add zspheres to the chain.

However, If I open up a Zsphere and do the exact process, I get different results. The added zspheres are all at the same size .

The other thing I noticed Is when you select a joint zsphere, it highlights the above chain in red . (which does not happen by default)

Does anyone know how this was done?