C-4, sometimes simplified as C4 and other times referred to by the general term plastique, is a type of plastic explosive. Despite being one of the first plastic explosives developed, in this case during the Cold War era of the late 20th Century, it was still occasionally used by the USCM during the late 22nd and early 23rd Centuries. Often this was in situations where supply lines were stretched thin or had been cut off all together, such as during the Xenomorph outbreak on Lethe in 2198. This expedient was made possible by the fact that C-4 was still popular out on the colonies as a relatively low cost and easy to use explosive for mining operations and demolitions. At least one subsidiary of Weyland-Yutani was known to be still regularly manufacturing C-4 explosives in the early 23rd Century for commercial and military users.