diff --git a/README.md b/README.md
index 2a674d0..9eeef35 100644
--- a/README.md
+++ b/README.md
@@ -4,3 +4,6 @@ Implements the old 7/8ths LAG filter but squared and a 15/16 squared lag filter
 i.e. two pole versions.
 
 Optimised for 8 bit implementations.
+
+Also feeds the output of the 15/16th squared lag to a 0.01/0.99 double precision lag that
+has a very long RC time