Adding filterable attribute to layered navigation, invisible on product page

Question

I know that you can add a drop down to your product pages with attributes like color and size.

What I would like to do is make some products on my site filterable through layered navigation without anything appearing on the product page.

For example.

Size: Full sized (100)
      Half sized (25).

Is there a way to do this through vanilla Magento? or

does it require some custom coding/module?

Answer 1

Set Use In Layered Navigation for the attribute in question? It's in Front-end Properties