Diaphragm Springs
These are spiral wound springs using four to eight pieces per set, made from heat treated high carbon steel and come in various shapes and sizes, delivering differing spring tensions depending on the size of the bike and the horsepower of your engine.

It is important to note that you cannot change the basic shape of these springs to gain any performance advantage but what you CAN do is buy an EBC Brakes CSK kit which has slightly thicker winding material and delivers 10 – 15% more clamp pressure.