Just like each piston skirt, the piston crown is exposed to different mechanical and thermal loads in each area. The highest level of thermal (heat) and mechanical (pressure) stress is concentrated near the center of the piston crown. JE found the best way to handle these loads is to create a piston crown that is contoured according to these stress levels. In the location where stress is high (the center) the crown is thicker; in low stress areas the crown is much thinner. This design approach is one reason that JE's asymmetrical pistons are both strong and lightweight.