Abstract: A wrench includes a head, a strain-vulnerable unit, at least one sensor, a handle set and a display. The strain-vulnerable unit includes a first end attached to the head, a second end at an adequate distance from the head and an aperture defined in the second end. The sensor is attached to the second end of the strain-vulnerable unit for detecting strain in the second end of the strain-vulnerable unit and sending a signal. The handle set is connected to the strain-vulnerable unit. The display is provided on the handle set and electrically connected to the sensor.

Abstract: A tool kit includes a handle, many bits and a torque-indicating extensive apparatus provided between the handle and a selected one of the bits. A torque-indicating extensive apparatus includes an extensive rod, at least one sensor and a display unit. The extensive rod includes a first bit-engaging section, a second bit-engaging section and a connective section formed between the first and second bit-engaging sections. The sensor is attached to extensive rod and used to sense a value of torque in the extensive rod and send a signal. The display unit is electrically connected to the sensor and used to show a reading of torque based on the signal.