Insert the string through the post hole?? wrap around once?? then lock by tightening with the thumb screw.</br>Locking machine heads utilize the famous 18:1 Rotomatic design with a "umb screw" mechanism.</br>Perfect replacement for the most standard machine heads. Chrome?? 3 Per Side.</br>Includes all mounting hardware.</br>Mounting screws and threaded hex peghead bushings with washers are included.10mm-diameter (13/32" pegholes required</br></br>Product Description</br></br>Chrome?? 3 Per Side. These locking machine heads utilize the famous 18:1 Rotomatic design with a "humb screw" mechanism which locks the string into place. Insert the string through the post hole?? wrap around once?? then lock by tightening with the thumb screw. Perfect replacement for the most standard machine heads. Includes all mounting hardware.</br><br/>http://www.amazon.com/gp/product/B002RX7JD4  is