[RWP] Does anyone know where to set length of recording?

[Indigo]

For recording audio and midi loops, I want to limit the length of 
recording, so Reaper will stop recording after 1 or 2 measures.
In Options/Preferences/Project Settings, there seems to be a length 
parameter in several places, I believe in item settings, I think in 
Track settings, but I don't know if these are the recording length 
settings I need, or understand the numbers in the edit boxes.

Could someone please tell me where I will find that setting?
Thanks,
Indigo