Traditionally, lethal pills are oval capsules, approximately the size of a pea, consisting of a thin-walled glass ampoule covered in brown rubber (to protect against accidental breakage) and filled with a concentrated solution of potassium cyanide. It is important to note that purpose-made lethal pills (of the rubber-coated type) are never swallowed whole. Instead, they are first crushed between the user's molars to release the fast-acting poison contained within. Brain death occurs within minutes and the heartbeat stops shortly after.