To give soldiers more flexibility in the field, engineers at the United States Army Armament Research, Development, and Engineering Center (ARDEC) are designing the first new lethal hand grenade in more than 40 years.

There are many different types of grenades used by the U.S. military. The most prominent grenades used in combat are concussion and fragmentation models. Fragmentation grenades explode releasing ball bearings and shrapnel to eliminate enemy combatants. These typically have a lethal radius of roughly 49 feet.

Concussion grenades on the other hand use a powerful blast to kill or incapacitate. These devices have a rather small kill radius, meaning soldiers can use them in rather close proximity without fear of being caught in the lethal blast zone.

The grenade currently under development — known as the Enhanced Tactical Multi-Purpose (ET-MP) hand grenade — looks to combine these two models for greater combat flexibility. Soldiers will have the option to instantaneously switch between either the concussion or fragmentation setting by simply flipping a lever on the device. Currently soldiers carry only a single M67 fragmentation grenade. The MK3A2 concussion grenade was taken out of service in 1975 because of an asbestos hazard.

The ET-MP will also incorporate a few other design upgrades as well. Unlike the fragmentation grenades in the field, the next generation ET-MP will be designed for ambidextrous use. At the moment, grenades require an alternate arming procedure for lefties. Also, the fuse timing in the ET-MP will be completely electronic for greater reliability and precision. And the detonation time can be reduced down to milliseconds.

The ARDEC plans to transition the ET-MP to Project Manager Close Combat Systems by the 2020 fiscal year.