C-4

From Lostpedia

C-4 block in The Flame basement ("Enter 77") (promotional still)

C-4 used for Sayid's suicide bombing mission. ("The Greater Good")

C-4, properly known as composition C-4, is a plastic explosive developed in the 1960s as an improvement to a pre-existing plastic explosive called Nobel 808. C-4 is a combination of explosive, a plastic binding agent, a plasticizer, and a marking chemical added to ease detection.

Like all plastic explosives, C-4 is extremely stable. Called an insensitive explosive, C-4 is very difficult to trigger by accident. Impact and fire are separately not enough to detonate C-4, but the combination of the two can create the necessary circumstances for detonation.

Uses in the series

Essam Tasir and Sayid were supposed to carry out a suicide bombing mission with a truck full of the C-4 explosive. Essam killed himself before they could carry out the plan. ("The Greater Good")
C-4 was the explosive used in the self-destruct system built into the Flame communications station. Several blocks of C-4 were strategically placed at the join between the subsurface section wall and the ceiling. The size of the blocks indicated a standard two-kilogram demolitions charge, common to military units. A series of these blocks would be more than sufficient to destroy the station. ("Enter 77")
Locke removed at least one of the C-4 blocks from the Flame station before it was destroyed. Rousseau suggested using this explosive to destroy one of the pylons in the sonic barrier, but the plan was deemed too dangerous. ("Par Avion")
Locke used C-4 he obtained from the Flame to blow up the Others' submarine. ("The Man from Tallahassee")
A C-4 bomb was found in the armory of the Kahana. ("There's No Place Like Home, Part 1") Desmond Hume and Jin Kwon's efforts to defuse the bomb were unsuccessful, though Michael Dawson did manage to delay the bomb's detonation by freezing its battery with a tank of liquid nitrogen. A "dead man's switch" device comprising a heart rate monitor and radio transmitter strapped to Martin Keamy's left arm caused the C-4 to explode, upon Keamy's death in the Orchid, sinking the Kahana and killing several innocent people, including; Michael and presumably Jin. ("There's No Place Like Home, Parts 2 & 3")