[Elecraft] CW Filter and Roofing Filter

[rclark01 at comcast.net]

Hi all: 
I currently own a Yaesu FT-950 and am considering selling it to move the the Elecraft K3S line. My question is about filters. My FT-950 has a roofing filter and a variable CW filter down to 200hz. Quite frankly, I can't tell much different when I switch in the roofing filter but the variable CW filter makes a big difference. I also have a 1970's TenTen Century 21 which has a 500Hz filter that, to me, seems to do a better job than the FT-950. So..when I read that a 500 Hz roofing filter is an option for the Elecraft K3S, what am I actually reading? Could there be a 500Hz roofing filter and a 500Hz CW filter or are they the same? In several Youtube videos, I've seen operators using the variable width the filter signals. What am I seeing? Are they adjusting the roofing filter or the cw filter? And...is the cw filter variable (like my FT-950) or fixed (like the Century 21)? 
Thanks! 

Robert NJ4j