Please explain this to me a little more. Is this so I can rev my motor higher or how does it work?

 

A trans brake has a solenoid that when activated (pushing the button) locks first and reverse together.
You bring the revs up to the desired launch RPM and release the button which disengages reverse and away you go. Hopefully wheels up.

 

So.......can I hold my RPM's at 6000 with that and launch at 6000? Lifting the wheels is what I want:-)