Abstract: A shock sensor has a shock sensing magnetic mass that rides on the inside of a glass tube that is sealed about a reed switch. The reed switch has a first stop positioned so that the shock sensing magnetic mass when resting against the first stop does not cause the reeds of the reed switch to attract. A spring extends between the shock sensing magnetic mass and a second stop. Acceleration causes the sensing mass to accelerate toward the second stop. The motion of the magnetic sensing mass causes the switch reeds to attract and close the reed switch. The entire shock sensing mechanism is hermetically sealed within the glass capsule of the reed switch. The reed switch within the glass capsule detects movement of the shock sensing mass.