An electrical connector for connecting a flat-type circuit board includes a pressing member to press the flat-type circuit board to a member to be connected. The lithium mixed transition metal oxide of the present invention has a stable layered structure and therefore exhibits improved stability of the crystal structure upon chargedischarge. A user provides a key that is not easily able to be guessed by third parties. The actuator includes at least one projection member. A first, a second, and a third lens are disposed sequentially, the first lens disposed toward an object, and the third lens disposed toward an image surface. The method and system which guarantee confidentiality as long as there is no collusion between agents working for a large number of reputable companies whose references can be easily checked on the Internet before proceeding to the order.