Do you have to buy filters seperately,or does it come with a set of filters.

Comes with the mask

This retailer has confirmed it does indeed include the filter cartridges. You will want to replace them when they become damaged, dirty, or difficult to breathe through. Thanks for asking!

This respirator comes with the filters. They will eventually have to be replaced, but they last a long time, depending on how much you use it. This is a really good respirator, and Lowes sells the replacement filters.