This air fresher creats up to 20 millions/ cm³ negative lons Helps to eliminate PM2.5 air pollutants, smoke, odors, dust,etc. Silent operation and easy to use No extra filter needed If you want to have a better immune system in the flu season, stop allergies from bothering you, boost your metabolism, this portable device is a reasonable option. Product Specification: Working voltage: DC5V Power: Less than 1w Battery capacity: 250mAh Negative ion concentration: 20 millions/ cm³ Life time:24-30 hours Charging time: 1 hours Colour:Silver Material:ABS Size:40x27x70mm Package Contents: 1 * Personal Air Purifier with Chain 1 * USB Charge Cable 1 * Manual Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.