Tail fuzes of this type are vane armed and inertia fired. Arming is mechanically delayed by reduction gearing.
AN-M102A1 is an earlier model having 24 single threads on the arming stem and an eight bladed vane requiring about 720 revolutions to arm.
The M100, M101, and M102 fuzes had a fixed delay of 0.1 second, and had 24 single threads on the arming stem. They had eight broad vanes with less pitch, and required approximately 720 vane revolutions to arm. AN-M100A1, AN-M101A1, and AN-M102A1 incorporated the interchangeable Primer Detonator M14. The A2 modification then reduced the number of vanes to four, and the number of threads to 16 double threads, thus decreasing the arming time to approximately 150 to 170 vane revolutions.