I agree with Lumpy , sure the inexpensive-ness is worth considering however any firearm even a plinker could potentially be needed to protect property life liberty etc etc , would a second guess be worth it ?? I used to have M44's on my AR but switched them out because I just could not trust the ongoing rigidity of the plastic and felt they could rotate with time and a vertical foregrip attached , which they didn't and probably never would have but I kept second guessing them. Would you keep a dog you didn't trust ??
I am sure they are very popular with US soldiers in Iraq they reduce weight and are alot cooler than an RAS and offer some mounting options standard handguards dont, so not to disrespect any soldier who takes out his automatic weapon for his company and country and those ungrateful bastards freedom but what do they care about accessories or rigidity or rotating ? They are using them in a real world scenario , which would make everyone a lot less critical about nominal tolerances . But Lumpy hit it , if your just going to go to the range - jump on them they work great for that.