Be VERY careful with their guns my friend. When you first pick them up, you might think to yourself that they're not bad, considering the price and all.
But inside its god awful. A closer look reveals that the receiver is bumpy and not well made. The innards have proprietary parts in places where it is completely unnecessary (probably them trying to get you to buy their replacement parts when they fail, which will be very often). Plastic everywhere. The EBB is laughable. On their M4 platforms, its an adaptation of CA's design, but even worse.
They're much better options out there. Despite a handful of good reviews, after a few games, the gun will most definitely die on you.