Round air filter specifically designed for PM2.5対策 (PM2.5 countermeasures) S size Unused, but the outer bag is dirty. I purchased the wrong size, so I stored it without using it. - Brand: Kurita - Model: Air Filter 2.5 - Size: S - Heat resistance: 100℃ - Features: PM2.5対策 (PM2.5 countermeasures) - Mounting type: Round type only Please consider purchasing only if you understand the dirt, etc. Thank you for looking.