I Ag Series Silver and fine silver possess very high electric and thermal conductivity. Low and stable contact resistance and good processing and welding performance. Because of a little nickel added into silver, fine silver has higher intensity and thermal-resistance performance than silver under same contact resistance. Therefore its fusion resistance and arc burning resistance are better than that of silver. Under the same application condition, fine silver can take the place of silver. II AgNi Series AgNi material with 10-40% of high melting-point metal nickel has high electric conductivity, low contact resistance and little burning loss. This material has little transfer when connecting and breaking direct current. AgNi material are widely used to AC and DC low-voltage devices, such as relays, instruction switches, can switches, assisting contactors. Instrument switches, optical control switches, temperature controller and washing machine timers, etc. III AgCdO Series AgCdO is the most used contact material at present. CdO obviously increased the fusion resistance or cohesive resistance of the contacts at the moment of getting through big current. The sublimation of CdO cools the contact surface. Lowers the arc energy and extinguishes the arc. Therefore AgCdO can meet the main requirements of low-voltage apparatus to contacts. Such as arc burning resistance at big-current switching-on, low and stable contact resistance under various loads and good arc extinguishing performance. Since Cd pollutes the environment. It is being substituted by other materials.