This cool tool is a specialty screwgun. It uses a strip of screws (figure A) preventing you from looking for the next screw. Having them all in one area saves time.
The screws feed in through the bottom of a channel (figure B) attached to the gun. Set the first screw on the strip at the second position, so that when you advance it it'll be the first screw to go.
Note: you can set the nose to use screws of different lengths.
This screwgun also countersinks the screws so they're easy to hide with drywall mud. Adjust the depth of the drive setting (figure C) to countersink the screws to the depth you need.