The filter insert can be used in alternation with the original filter or as a replacement.  

Part Numbers:

WE 0306 - WFF100 Vortex Filter

WE 0301 - WFF150 Vortex Filter

15801 - Garden Downspout Filter 

FE 0301 - Poly and SS Downspout Filter, Standpipe Filter 

Spec Sheet

Downspout Filter Insert