Angle Torque Wrench

This is an Angle Torque Tool.
Make sure that the stop rod (black color L rod) is slightly shorter than the ext bar and socket as shown below. Otherwise the socket will not sit at the bottom of the cylinder head bolt properly.
The stop rod can be placed outside of the cylinder head wall for support or it could be placed inside whichever is convenient.
This tool is typically attached to a 9½ inch ext rod and a ratchet wrench of 200Nm or more of torque capability.

Adjustment is normally done by :  (for one hand quick operation) where the other hand is holding the tool proper.                     

Turning knob anticlockwise until it stop followed by

Turning Dial anticlockwise to '0'

Then

Turning knob clockwise until it stop followed by

Turning Dial clockwise to '0'

Make sure there is no slack by pushing the knob in the tightening direction - clockwise before turning the wrench.