[Elecraft] [K3] KFL3A-1.0K 1 kHz, 8-pole roofing filter : Purpose?

[S Sacco]

Ever since I started looking at the K3, I've been wondering about the
purpose of the 1 kHz roofing filter.

It's too narrow for SSB, and, for me at least, WAY too wide for CW.

What would it be used for?  RTTY?

I have the 2.8, 400 and 200 filters in my K3 as of now.  I'm
considering adding the 1.8, but will probably wait until I get some
experience with the 2.8 and DSP.

Thanks,

73,
Steve NN4X
K3 SN 458