Glock PG4030103MOS: The Glock 40 Gen 4 is chambered in 10mm and has a full 6-inch barrel for an improved velocity.The G40 Gen 4 is a powerful yet easily carried pistol; perfect for the outdoor person, hunter, or sport shooter. It is designed to give the handgun hunter the ultimate choice in semi-automatic gaming pistol and has proven to be more than capable of taking down game such as whitetail deer, russian boar, and feral hogs. Glock engineers have developed the Glock Modular Optic System (MOS) to simplify mounting of popular optics without costly custom machining of the pistol\'s slide. The MOS is offered with cover plate when no optic is mounted and four plates options to comply with the specifications of some of the most trusted optic manufacturers in the industry. MOS gives you the option of adding tall iron sights allowing the optic and the iron sights to co-witness.