 The RPG-7 usually has an impact (PIBD) fuze in parallel with a 4.5 second time fuze, so detonation should occur on impact, but otherwise takes place after 4.5 seconds.Military weapons containing explosives have fuzing systems including a series time fuze to ensure that they do not initiate (explode) prematurely within a danger distance of the munition launch platform.In general, the munition has to travel a certain distance, wait for a period of time (via a clockwork, electronic or chemical delay mechanism), or have some form of arming pin or plug removed.