Connector including external housing and plural internal housings

A connector comprising:

• an external housing including a plurality of cavities;
• and
• a plurality of internal housings to be respectively inserted into the plurality of cavities, each internal housing accommodating a plurality of terminals, wherein
• a retainer extending in a housing insertion direction of inserting each of the internal housings into each of the cavities is formed on an inner wall surface of each of the cavities,
• a groove part for receiving the retainer when each of the internal housings is inserted into each of the cavities is formed on an outer wall surface of each of the internal housings,
• wherein the retainer of each cavity of the external housing and the groove part of each internal housing are configured such that,
• when each of the internal housings is inserted into each of the cavities, the retainer is inserted into the groove part, and thereby the plurality of terminals accommodated in each of the internal housings are secondarily locked by the retainer,
• wherein the secondarily locking is such that when a force is applied to pull out a terminal accommodated in an internal housing, a surface of the terminal comes into contact with a surface of the retainer to prevent the terminal from being pulled out of the internal housing,
• the retainers of the plurality of cavities have different shapes from one another, and
• the groove parts of the plurality of internal housings have shapes complementary to the shapes of the retainers of corresponding cavities.