These fans run on brushless bearings, meaning they run quietly and have a long lifespan.
They are lightweight and can be mounted to a moving carriage without impacting its performance.
They are ideal for cooling 3D printer hotends, and are also great for cooling the print itself (if you want to print quickly or are printing tricky overhangs).
They can also be used to cool your electronics - RAMPS, stepper drivers, and such. If your stepper drivers are overheating you'll see layer shifts in your print - and adding a fan such as this is one of the easiest ways to correct this!
Simply put - adding a couple of well-placed fans will allow you to run your printer faster, keep it running longer, and get a better quality of print. Perfect!
These fans come with a 2-pin JST connector - the type often found in hobbyist electronics on fans, LiPo batteries, and small motors. If you do not have a matching connector available you can either cut the end off and solder on your own longer cables, or alternatively standard breadboard wire (solid core) will push straight into each socket of the connector, making a solid and stable connection.