Gotoh 381 Series Tuners. 6 In Line. Set of six. 16:1 ratio. Will fit headstock holes that are drilled out to 10mm diameter. They feature Gotoh's revolutionary Rock Solid posts for unrivalled tuning stability and "Lubri-Coat" technology which reduces friction between the gears resulting in an ultra smooth feel and minimal back lash. Screws, washers and bushes included. This set features height adjustable posts to select optimum height of each string for perfect balance over the top nut - use supplied allen key to loosen the internal nut via the back of the tuner. This frees the tuner post to rotate which raises or lowers the height of the string hole. Once the desired height has been chosen, lock it off with the allen key and use the tuner as normal. As well as being height adjustable, the posts are locking - simply insert the string through the hole, pull to tension by hand and begin tuning. As you tune, only the locking cam in the post turns. Once the string begins to turn, it can be tuned to pitch. In less than one revolution of the post, you will be in tune and locked.