Help reading Noise Characteristic graph for sub-nanovolt amp

[ArthurRukin]

These are the links to the specific product I am looking at and its noise characteristic graph.

http://www.emelectronics.co.uk/a20.html
http://www.emelectronics.co.uk/graphs/a20graph.htm

I understand the graph for the most part, but I am confused about which one of the four filters that are listed in the product description is used to create the graph. The filters give different time constants, but none of them are 20 seconds, which is what the time constant is in the case of the graph.

My ultimate goal is to try to figure out what the graph would look like with a 1k filter setting in the amp.
Any help is greatly appreciated. Thank you!

 

[Tom.G]

I tried but they are mixing reference points and their graphs can be only roughly interpolated. I recommend you ask the manufacturer, or find a different one.
That said, here is a paper that may help explain things a bit. http://noisecom.com/~/media/Noisecom/noisebasics.ashx

EDIT: added link