This is a tremolo unit that was installed on a History premium grade guitar (a guitar made by a private workshop called Tsubasa Guitars), the highest grade of History guitars. It has a very luxurious feel. Because it's a vintage specification, the string spacing is 11.3mm. The string spacing is different from my other guitars, so it feels odd, and I've decided to sell it. I bought the guitar three months ago, so it's like new.