When the pin is pulled and the top cap removed it reveals a small propeller which is locked by a set back pin.
On firing the pin drops back into the body and allows the propelle to rotate. This rotation winds down a firing pin into the body arming the bomb. On impact an inertia pellet shoots forward and hits the firing pin. the flash from the percussion cap travels through the inertia pellet and ignites the detonator below it exploding the bomb. Fragments are produced from an internal frag coil as well as the body and fins.
