Airsoft Locos gives a rather very quick overview of the GHK URGI MK16-Style 10.3 Inch GBB Rifle... "The long-awaited full MK16 built featuring the ever-popular URGI style upper receiver is finally here built off of the GHK system. The MK16 features the URGI which stands for Upper Receiver Group Improved is the latest platform used by special operations forces in the United States in maybe different capacities and roles. Being built upon the GHK system you will be thrilled to know that this rifle will perform exceptionally. GHK is renowned for its high gas efficiency and incredible FSP consistency. Besides being a hands-down performer, the rifle is also built to last and be more than capable to be your workhorse GBBR for skirmishes, milsims, or just as a training platform."