Happy-top 4-inch Vanes 3 Speeds Mini Hand Held Portable USB Fan with 18650 Rechargeable Battery and USB Cable (Green) Dual Power Sources, plug in with Adapter(Not included) or use with Li-ion 18650 Batteries (included) 10000 Hours lifetime, 100% pure copper brushless motor,3150RPM/min (other USB fan is below 2000RPM/min),high energy conservation, silent cooling. High efficient and 2-8 Hours long working time (Depend on the mode you use) With 3 mode wind ajust: strong,middle,little, the highest wind speed 4.2M/s, blowing from 3 m,effective range Above 3M It is perfect for someone who wants a short range but powerful breeze on the face and goes perfectly on a desk, camping tent or nightstand.