Locking Tuning Machines For Electric or Acoustic guitars with 3 by 3 Tuning Mechanism 

• Peg Hole Size : 10mm(25/64 inch) 
• Gear ratio 18:1, the retaining mechanism lock the strings in place, preventing them from slipping, improve tuning stability and make string changes much faster. This differs from most other similar looking products
• Zinc alloy made streamlined body, stainless steel lock button cover, with great electroplate finish
• Package includes: 6pcs machine heads set (3L + 3R) and mounting accessories.

The ones offered here differs from others you may find elsewhere with similar looks. 

• The locks are MORE DURABLE AS THEY ARE MADE WITH STAINLESS STEEL. Many others are made of plastic
• Each set is separately oiled/greased so they will feel smoother than others