The Nerf N-Strike Elite Alpha Trooper CS-12 is a highly rated 12-dart Nerf gun. It allows for long range, high power rapid fire. Holding down the trigger and pumping the slide repeatedly will activate "slam-fire" mode.
The typical coloring of this gun is orange and blue with silver trim and it is labeled with the name of the gun along the side of the body. The gun also has an orange jam door on the top for removing jammed darts, a hole in the bottom for interchangeable magazines, and a module on the back for an optional gun butt upgrade.
Help for common problems can be found on the troubleshooting page.
A teardown of the gun can be found here.
Nerf Wiki has additional general information on this gun.
Outback Nerf contains an in-depth review for the gun.
Inspiration for modifications can be found here.