Product filtering can allow you zoom in on specific visitors and their behavior on your site, and create ads that more specifically target their interests. Here are a few things to keep in mind when Product Filtering.
Don't make product sets too specific. Try to choose at least 4 in-stock items that are not variants of the same item.
Create product sets from broad categories in your store like All Women's Shoes, All Children's Clothing, or All Products Under $50 to ensure you will have enough specific traffic.
Filters aren’t case sensitive. Filtering for the brand “Nike” will also include items from “nike”.
If you have a large inventory, don’t apply many filters with "contains" or "does not contain" logic because they may slow down filtering.