The refractory component (W, WC, Mo) provides durability to the contact, while the silver provides excellent thermal and electrical conductivity. Relative to many other contact materials, silver refractory materials are more electrically resistive due to the refractory component. As a result, high contact pressures are typically required to overcome this resistance. When selecting these materials, consideration must be given to the increasing contact resistances that are experienced during service life. The correct selection of compositions, refractory components, and particle sizes can often help to overcome this phenomenon.