Black - Classic mini oval vintage button with sealed housing and 45¾ fixing tag. 6-in-line.E-Z-LOK™ Designed to work on guitars of all styles E-Z-Lok™ machineheads are the ultimate in the quest for perfect tuning stability.Unlike ordinary tuners, each E-Z-Lok post has two holes. This simple concept transforms each tuner into the tuner you want it to be. Want to string conventionally?Then OK, do it! Want to change the tension over the nut? OK, use the upper hole to decrease the tension, use the lower hole to increase the tension.Want to stay in tune when using a Vibrato/Tremolo system? Then OK, you can do this too. Eliminating the wraps around a tuner post is a must do when using a vibrato system.Thread the string through either the top or bottom hole, pull the string tight and make a wrap around the post then thread the remaining string through the second hole. Pull tight again and you now have a locking tuning key.