"Heel struts" (also sometimes referred to as High Heels) are part of Transformer anatomy. They are common on Transformers who have a relatively low foot surface area whose point-of-contact is concentrated somewhere forward of the ankle joint. Heel struts are more common on Transformers with small frames or a high center of gravity. It has been noted that a disproportionate number of female Transformers have heel struts... but female Transformers also tend to have smaller frames and lack the big clunky feet of many male Transformers. Also, they make their butts move sexy when they walk.