Compared to the original Cougar vehicle, the British variant is fitted with large, vertical armor plates that cover the large vision blocks and weapon firing ports. This is in line with British Army doctrine concerning the role of the APC/MICV, specifically that it is to carry troops under protection to the objective and give firepower support when they have disembarked. The Mastiff is fitted with a turret sporting either a L7A2 GPMG (General Purpose Machine Gun), L110A1 Light Machine Gun, L11A1 Heavy Machine Gun or L134A1 40 mm Grenade Machine Gun. One aspect of the British Army's approach to APC/MICV units (which differs to that of the United States) is that the ability of the average soldier to fire accurately out the ports of a moving IFV has been questioned. The large armor plates add side protection from RPGs or IED explosions.