This Module allows you to enable Filters on all parent and sub categories, without having to assign them individually to every category.
Just assign filters to the products and they show up on the category pages.
for more details on opencart
please visit Opencart modules
For a better explanation:
Default : Every time a new filter (ex: size or price or color etc) are created or assigned to a product, you have to also assign those filters to the parent and sub categories of the product. And all the filters assigned to the category are shown on category page irrespective of products.
With This Module: You just have to assign filters to products and the category pages will auto populate the relevant filters of the products and show them.