These super tuners are recognized as such around the world. The SG381 feature a 16:1 gear ratio and has evolved through improvement without compromise at any stage and come equipped with a considerable application of high-technology as standard. With the improvement of precision fitting gears, marvelous touch on playing---they have gained a considerable reputation and are trusted as the No.1 machine head by many musicians all over the world. These come with a metal keystone head and are perfect for your six inline setup. Mounting hardware included.