First of all, for those of you who have not heard about the ARM 4000 XL, it is an arm-mounted water gun that you pump by flexing it. It also connects to a 68oz. backpack. The range of this soaker is very good. At a 45 degree angle, it shoots 42 feet. To get an idea of how far that is, it is about 5 feet more than most CPS 2100s and equal to that of most CPS 1200s. The nozzle size is about 1.1X. One of the minuses of this gun is the way you pump it. You have to adjust the gun so it fits perfectly on your arm. If you do not, pumping will be very difficult. This gun is compatible for both right and left handers. A big advantage to this gun is that you can pump while you run. Since, naturally, you flex your arm when you run, you pump the gun at the same time.

All in all, this gun is recommended if you can afford to have one arm taken.

Pros

Backpack
Light
Good Range
Pumps while running
Great Shot Time
For Right and Left Handers

Cons

Small Output
Pumping sometimes difficult
Weak build
Whole arm is taken