"A refined explosive compound it greatly increases the amount of energy delivered onto target. It adds to the destructive power carried by mobile infantry and engineers."
— In-game description
The 'Improved Demolitions'specialization (also known as Explosive Mk2 or EXPLMK2) is unlocked at Rank 17 of Battlefield: Bad Company 2's multiplayer. It Increases the damage dealt by all explosive weapons by 25%. This is useful for the Engineer's Launchers, the Assault's 40mm Grenade Launcher and the Recon's Mortar Strike and C4. This specialization provides little benefit for the Medic class, as the only usable explosive is the grenade.
Improved Demolitions are coupled to the player, not the weapon. If an Explosive Mk2 user were to acquire a new weapon on the field, the specialization would still be in effect. Likewise, if a player were to acquire a weapon belonging to an Explosive Mk2 user, they would not gain its effects.