This app is the missing link for us. We use it to display related products on the product pages. Now, we can control exactly which related products appear.
The standard code that comes with most Shopify templates just grabs random products from a collection. A collection is too broad of a definition for related products.
We needed help to get the template code (snippet) modified. Support at Helium Dev got us up and running. We did the final CSS customizing. Works great!