The Disc Grenade is an explosive anti-vehicle device that disables vehicles by magnetically adhering to their undercarriage and detonating after being attached.
During an attempted assassination, S.H.I.E.L.D. director Nick Fury tried to escape from several HYDRA agents disguised as Washington, D.C. police officers in his SUV. After rounding a corner, the Winter Soldier approached, firing a Disc Grenade. The Grenade attached itself to the undercarriage of the vehicle and exploded, causing it to flip over.
The disc grenade is a specialized explosive device designed primarily to disable automobiles or other motor vehicles, including a variety of mid-sized to large cars or trucks. The grenade appears as a large flat disc, about 8-10 inches across, with narrow orange lights around the outside edge. The grenade possesses a set of four magnetic plates, allowing it to adhere to metallic surfaces, as well as giving it the ability to jump the distance between the ground and the undercarriage of a vehicle.
The grenade is typically launched from a specially modified standalone grenade launcher. When launched the grenade's momentum allows it to slide across a level, paved surface until it is able to make contact with and magnetically attach to an appropriate target, after which it will detonate. The detonation of one of these grenades creates an explosion powerful enough to potentially lift a vehicle into the air and either flip it over or knock it off the road entirely, or, on larger, heavier vehicles destroy and disable a portion of the drive mechanics.