A terminal unit (30) has inner conductors in a dielectric (36) and is mounted in a first or second housing (10, 20). The first housing (10) includes a first locking lance (14), a front retainer (17) and a first accommodation chamber (13). The second housing (20) includes a second locking lance (22), a second accommodation chamber (21) and a side retainer (25). First and second locks (45, 54) are formed on a surface of the dielectric (36). The terminal unit (30) inserted into the first accommodation chamber (13) is retained by the front retainer (17) restricting deflection of the first locking lance (14) and the first lock (45) locking the first locking lance (14). The terminal unit (30) inserted into the second accommodation chamber (21) is retained by locking the first lock (45) with the second locking lance (22) and locking the second lock (54) with the side retainer (25).