This is made of metal foil plates that are separated by sheets of mica (the dielectric). The whole assembly is encased in moulded plastic. Since the capacitor parts are moulded into a plastic case, corrosion and damage to the plates and dielectric are prevented. Also the moulded plastic case makes the capacitor mechanically stronger. Various types of terminals are used on mica capacitors to connect them into circuits. These terminals are also moulded into the plastic case.