【2 in 1 Dual USB 40mm Fan】With the light and compact design, ELUTENG computer fan USB 40mm is perfect for narrow place. Its square design allows it to be laid flat or stand upright. USB powered, plug and play. 2 fans are connected to run together at the same time for better heat dissipation. | 【Upgraded Cooling Effect】We add a metal heat sink at the bottom of USB fans cooling quiet, elevating the bottom air circulation to reduce the temperature of device and achieve the purpose of heat dissipation. Package also includes a silicone heat sink to achieve effective cooling when in use. | 【3 Level Adjustable Speeds】The upgraded USB cooling fan with 3 speed gears (low, middle and high), which is specially designed to control the airflow levels. The wind speed is 4500/5500/6500rpm. You can choose different air speed levels according to your operating environment. | 【Safe & Durable】This electronics USB cooling fan features metal grids on the front side, preventing the blade from hurting your fingers and damaging the wire when working. It adopts high quality double ball bearings, delivering durable use and longer service life. | 【Wide Application】Size: 4 x 4 x 1cm per fan. The computer fan USB powered is ideal for cooling PC/laptop/TV box/receiver/mobile phone/PS4/projector/router/hard drive enclosure, etc. Just plug in any device with a USB port to start cooling.