That’s a good question. I purchased an aftermarket kit containing a brushroll, all the filters, and side brushes off Amazon. Eifrthe 15-piece Shark AV2501AE... https://www.amazon.com/dp/B0BKW5ZS8W?ref=ppx_pop_mob_ap_share

It works. I don’t know how often it should be replaced. I thought I needed to change mine because I kept getting error messages that the brushroll was obstructed. In reality all I needed to do is clean out the roller end (the gray one). I couldn’t figure out how to get the end cap off, but it will pop off with the help of a screwdriver. I’m still using it and my spare is in a drawer.

Lastly, I don’t know about you, but I find “self-cleaning” hilarious.