Name and use of this panel

[3ARDUN2]

Curious as to the name and original use of this open cowl panel that covers the top of the dash as well as the lower w/s post bases. I remember talking to a Model A parts vendor at Hershey years ago and was told that they were used on open cab cowls when a w/s wasn’t used. He also said there different characteristics between the 1930 and 1931.