These are spiral wound springs using 4- 8 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 a EBC Brakes CSK kit which have slightly thicker winding material and deliver 10-15% more clamp pressure.
These are a dish shaped flat steel pressure ring and there are normally only 1 or 2 in a bikes engine, you should never add MORE springs on a diaphragm spring set up. If you do wish to upgrade the clamp load and your bikes is fitted with a diaphragm spring clutch kit buy an EBC Brakes spring kit, all of which are built with 10-15% more clamp pressure than stock.
Note: Any spring kit not listed can be indent ordered