Mechanical double joint system

A mechanical joint system, comprising:

• a first joint defining a pivot hole and a joint receiving hole communicating with the pivot hole;
• an arm being rotatable relative to the joint, the arm comprising a pivot portion and a pivot hole defined in the pivot portion, the pivot portion being received in the joint receiving hole, and the pivot hole of the arm and the pivot hole of the joint being aligned along a same axis;
• an engaging member comprising a pivot shaft and a fixing member, the pivot shaft comprising a shaft head and a shaft portion extending from an end of the shaft head, the shaft head being inserted into the pivot hole from an end thereof, the fixing member being inserted into the pivot hole from an opposite end thereof, and fixed relative to the pivot shaft;
• a plurality of teeth extending from an outer surface of the shaft portion of the pivot shaft;
• and
• at least one latching member mounted in the pivot hole of the pivot portion of the arm for engaging with the teeth.