the helios shield and truman cell never need to be replaced.other air purifiers rely on filters, just like these. they have to be replaced, and cost you hundreds of dollars, and they're filters that can eventually end up in a landfill. but with oreck's proshield plus filtration system you just remove the truman cell let it soak in some warm soapy water rinse it out ugh, look at all the nasty stuff it pulled out of the air and when you're finished let it dry and then put it back in. you just put it under water and you just clean it with water and that's it. it's very very easy. all i do is open it up, i pull out the truman cell, i go to the sink, i, i just use water, i rinse it off, i watch all the gross stuff come off of it, i let it dry and then i put it back in, and then, you know, your up and running, you can go do other things, and the proshield plus is ready to go when you need to use it. if you own the proshield plus, seeing that grime come off the truman cell can be proof enough that it's a great investment. and stay tuned because in jus