Free from Rast Sound.
FKFX are unique plugin tools, made by two guys escaped from audio industry. Download (Patreon Support possible) their plugins here.
The bx_subfilter is a free plugin that borrows from the “Filter” section of its larger counterpart, the bx_subsynth. It’s the perfect plugin for anyone who loves the bx_subsynth’s unique approach to low-end filtering, but doesn’t need the subharmonic synthesis.
You need to have a (free) account at Plugin Boutique.