I decided to get a laptop cooler since my laptop fan was coming on rather a lot. Not knowing much about coolers I decided to give this one a try since it's a reasonable price.
It's X shaped with a single fan. At the back-right are 2 usb ports, a on/off button and adjuster for fan speed. It's about 1 cm wider than my 15.4 inch widescreen laptop which is pretty much a perfect fit.
The cooler is powered by plugging the included wire into a laptop usb port and into one of the cooler's ports. The other cooler port can then be used as a normal usb port. Be aware that because the 2 cooler ports are both on the right, and the wire isn't too long, you'll have trouble if your laptop's usb is on the left. It would've been nicer if they'd included a port per side on the cooler. Luckily I have a port on the right of my laptop so it works well.
At the lowest setting the noise is pretty quiet but you don't get much fan power. You will be able to use it in most environments without disturbing anyone (pressing keyboard keys is louder). At the highest setting it's much louder but obviously does deliver more power. The knob that controls the speed is out of the way but accessible and it's not a slow-fast scenario, you can slide it to any speed in between.
For general usage you can likely leave it on a power setting nearer the lower end.
The cooling power is twofold:
1. It's a stable flat base where the laptop can sit on it's own feet and let the air flow underneath. Useful if you use your laptop on your lap or on uneven surfaces.
2. The fan blows air onto the bottom of your machine.
I haven't done temperature comparisons but I can say for certain that the fan comes on much less often now - even on the lowest setting. And the bottom of my laptop is now often much cooler - again even on the lowest setting with normal use.
One thing that caught me out is the cooler is slanted down from the back. This means you have to tilt the screen a little further back than you would normally and you type on a slight incline. You get used to it pretty quickly though.
Keep in mind that heat does reduce wear and tear in the system and particularly the battery which does suffer with more heat so if you are frequently getting a hot laptop base or the internal fan comes on a lot, you should definitely consider this or a similar cooler.
And if nothing else it provides a nice flat surface to rest your machine on.
4 stars instead of 5 because I'm not overly keen on the tilt, and the placing of the cooler's usb ports could've been better thought out.