BLUEAIR Classic 500/600 Genuine Particle Replacement Filter; fits 680i, 501, 503, 505, 510, 550E, 555EB, 601, 605, 650E

These are new and extremely lightly used!!!! !!!! I added these in my air purifiers in March but we replaced all blue air purifiers with a different brand within 1 day of placing filters in units. (We needed a bigger unit for the space) These were placed in previous air purifiers but used for less than 1 hour so they are about 99% new. Check out photos. My lost your gain. These retail for $100 each; yours for $50 each