Press & Twist type  (for slightly damaged screws) 

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１) Insert the bit into the handle grip.

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２) Place the bit tip into the screw head, then scrape away
     burs in the recess by twisting it back and forth lightly.  
     *Do not attempt to hit the bit with a hammer.

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３) After you feel the bit tip catches the corner of recess, 
     give a jerk counterclockwise while pressing firmly 
     downward.