Abstract: A twist breaking plastic guarantee seal having a cap portion and a depending skirt portion interconnected by ribs. A skirt portion has a greater inside diameter that the outside diameter of said cap portion and stop means are provided between these two diameters. The skirt portion is adapted for securement to a container neck exterior and the seal is broken by twisting the cap portion relative to the skirt. During application of the cap, to a container predetermined amount of axial movement of the cap relative to the skirt portion occurs, causing the interconnecting ribs to flex and weaken. The twisting of the cap relative to the skirt causes shearing of the ribs and allows the cap to be removed.