A method and system are disclosed for intelligently notifying first parties via automated telephone calls regarding an absence by second parties at an event with minimal burden on a third party who manages attendance issues for the event. The residual life indicator comprises a solid, surface active, waterproof support medium having a concentric pattern imprinted thereon. A variable distance detonation mechanism is coupled to the trigger and primer for allowing controlled detonation of the grenade a specific distance from the launch point thereof.