A subsea docking unit 2 including an electronic module for being removably connected to a subsea docking station 1 comprises a canister B containing electronics to be connected to the docking station, and a selectively, engageable locking device for locking the docking unit to the docking station. The locking device comprises one or more arm structures adapted for being pivotally mounted into a corresponding arm holding detail on said docking unit, and an actuator means for moving said arm structure in relation to one or more corresponding arm receiving and retaining details on said docking station, whereby a releasable locking engagement and disengagement of the docking unit and docking station is obtained. The docking station correspondingly comprises arm receiving and retaining detail adapted for receiving and retaining a docking unit. The docking unit and docking station are parts of a multiphase flow meter.