Some laptop computers get heated up if worked for a long period of time (be sure the built in cooling is working properly). To solve this problem there are many external cooling pads in the market. Almost every laptop cooling pad has one or more fans built into them and are powered by the USB ports of the laptop.
It is important to note the direction of air flow in your laptop vents before purchasing a cooling pad. With an understanding of the vents and the air flow direction, you will be able to understand that laptop cooling pads which claim to remove cool air from the bottom of your laptop may not be the one for you.
When you place a laptop on a flat surface, the distance between the laptop body and the table surface is less than an inch. Since hot air has the tendency of rising upwards, therefore you want a laptop cooling pad that moves cool air in the same direction as the warm air generated by your laptop.
Be sure to purchase a cooling pad that blows cooling air through the bottom portion of your laptop, which will in turn increase the airflow going into your laptop. The best cooling pads are designed in such a way to create a space between laptop and the cooing pad. This design does not restrict airflow.
Most Macbooks are designed so that the circulation vents are provided behind the keyboard, making cooling pads unnecessary.
I hope this is information is useful when you decide to buy your next cooling pad.