Connection boxes are used when sensors are mounted on hard-to-reach measuring points and are not operated permanently. If required, the user can connect to the sensors via the BNC sockets if a measurement is imminent. The PCB-691A50 Series boxes can be sealed tight if no measurement is taken. They are available with up to twelve channels and are suitable for wall mounting. As an alternative, the miniature boxes of the PCB-691A51 series are available with up to four channels.