Set of two 140mm USB-connected fans. With holes in the four corners, they can be mounted in any location, such as a breeding shelf. Perfect for animal racks or plant racks with indoor LED lighting. These are pure fans, so they do not emit cold air. With a diameter of 14cm and a thickness of 25mm, they provide a strong airflow. The brushless motor is very quiet, and the power consumption is extremely low, so you don't have to worry about electricity costs even with 24-hour continuous operation. Originally PC fans, they are designed for long-term continuous use and are highly durable. They are not rechargeable. You don't have to worry about battery depletion or degradation, so you can use them with peace of mind. 9cm fans and a 2-fan 12cm fan with a switch are also available. Please take a look if you'd like.