This simple upgrade allows the shooter to spend more time on target, reduce the number of steps in tactical reloads and has some 'way cool' factor to set your rig apart from the rest. It can be used by both right and left handed shooters.
Anyway enough of my rambling check out the video...
P.S. BTW my M4 is a model 2 from Stag Arms 5.56 with flat top upper receiver and removable handle/sight