The data transmission circuit has a test mode for offsetting variation of crossover voltages of the first and second data signals, which rises from threshold voltage distribution of plural transistors embedded in a transceiver. The lever has a first end pivoted in correspondence with a peripheral rib, a second end, which functions as a gripper element, disposed in substantial correspondence with the central zone, and an intermediate zone between the two ends, wherein the lever is connected to the stopper. A tubing capture is disposed on one of the opposing sides, aligned with one of said openings and extending outwardly from said housing, for grasping the tubing in order to prevent unwanted dislodgement of the tubing from said housing. The groove portions are arranged obliquely regarding either one of a horizontal direction or a vertical direction of the sensor body.