Is it a Combo box filter that I need on my database table?

I am trying to do another database for work, and I have a Table called Stock list, it contains two fields - Category and Product description. I need both fields to be a drop down box, so in category you can choose the category and likewise with Product description. What I need is that when the user chooses the category, it automatically reduces what is shown in the drop down box for Product description-so it only shows what is in that category. I think maybe what I need is a combo box filter, but have no idea how. So any help would be appreciated. Thanks.