C4 is a demolition charge used to destroy assets found in the AO. The charge has to be planted directly on the target and once placed, arms and detonates after a certain amount of time. The time it takes to plant the charge is affected by the demo skill of the Ranger planting the charge. It is advised to retreat rapidly after the charge has been planted to prevent suffering casualties from the explosion and to avoid the alerted VC forces.
C4 is less commonly known as Composition 4, which, in turn, is a variation of the Composition C family of plastic explosive. It is known as PE-4 (Plastic Explosive) in England and the UK, and is composed primarily of explosives, plastic binder, malleable plasticizer ingredients, and a taggant chemical.
It has a texture similar to modelling clay and is considerably sticky; as such, G.I. Composition 4 was commonly wrapped in olive drab packaging to serve two purposes - first, to avoid a mess of the malleable clay-like substance within the soldier's equipment, and second, to serve camouflage purposes as Composition 4 is quite bright yellow or off-white. It can only be detonated by a combination of extreme heat and shockwave, making it inert without a trigger.