Abstract: A triggering element for a portable heat pack having a sealed bag capable of transferring heat and a sodium acetate solution that generate a crystallization heat contained in said sealed bag. The triggering element comprises a thin, flexible strip of stainless steel; the strip having an oval shape with the length and a center portion formed in a bowl-shaped configuration with one surface depressed inward to form a concave shape surface and the convex surface opposite side with a protruded surface, and the depth of the center portion depressed inward. The strip has an the outer annular portion and a plurality of slits cut through said center portion.