The virtuosic pairing of Tolgahan Çoğulu & Sinan Ayyıldız Duo can certainly lay claim to be the world's first microtonal guitar and double-necked saz duo. Indeed it was Tolgahan Çoğulu who invented his instrument, an 8-string classical style guitar with layers of moveable frets that enable micro-tonal adjustments, allowing him to perform the varied scales (makam) of Turkish music whilst maintaining the sonic essence of the classical instrument.