A non-electric detonator connected to similar detonators with capsule 2 with having charge 8 and delay train 9. A tube 3 for transmitting a shock wave having an internal surface with a predetermined amount of a propagating explosive has one end mounted within capsule 2 adjacent to delay train 9. A seal 12 formed by collapsing a portion of tube 3 at a distance from its end prevents a shock wave accidentally created at capsule 2 from propagating to the rest of tube 3. Yet, the propagation of the wave is not prevented when it comes from the other end of tube 3. The distance from end 13a where seal 12 is formed needs to be selected for a predetermined explosive amount not sufficient to propagate the wave from capsule 2 but enough to propagate it when the wave comes from the other end.