ZBrushCentral

"question:" IPress, Transform:Fit in 3.1 ?

I found Transform:Fit while web searching . What does [IPress, Transform:Fit] do ?
I am looking for a zscript that can create a fitting object using the current tool .

I am using zbrush 3.1 and cannot find any “Fit” button under the Transform menu .

Is it available under 3.5 version of zbrush ? Where can obtain version 3.5 by the way ?

Thanks in advance for any answer.