This was one of the first upgrades I purchased for my SR25, and let me tell you, it rocks. If you're looking to turn your designated marksman's rifle into a real counter-sniper light MG, this is essential. I use this in conjunction with an 11.1v LiPo battery for an increased rate of fire, and let me tell you, no sniper lives to tell the tale. I originally found myself torn between getting this or getting a couple more hi-caps, and this was definitely the way to go, you can keep this thing winding while you fire and lay down as many rounds as your battery can handle. While I can see how a standard sniper or DM using this rifle wouldn't consider the added weight and size a favorable trade off, if you're more of an emplacement gunner looking to compliment a small squad who may not have a support gunner with adequate range to deal with sniper threats, this is the accessory for you.
Holds LOTS of ammo.
Handy push button winder can be attached to a fore or rear grip for easy winding.
For continuous firing, wind can be turned on or off on the magazine.
Solid ABS plastic construction, no problems so far durability wise.
Indicatorr on the back right of the magazine allows you to see how much ammo you have left.
Heavy, especially when fully loaded (could be a pro I suppose).
Not practical in the traditional use of the gun it is made for, more of a specialty for strange hybrid players like myself.