The lightweight M26 12-Gauge Modular Accessory Shotgun System (MASS) attaches to the M4 Carbine and zeroes to the host weapon. It can also operate as a stand-alone system. It comes with a recoil-absorbing, collapsible buttstock. The Picatinny rail on top allows attachment of accessory equipment to the shotgun. The bolt handle (charging handle) can mount on either side for ambidextrous handling.
The MASS enables Soldiers to transition quickly between lethal and less-than-lethal fires. It adds shotgun capability to their M4 without carrying a separate second weapon. Additional features include a box magazine, flip-up sights, and an extendable stand-off device for door breaching.