Sinn watch 900 pilot s leather the 900 is the largest instrument chronograph designed by sinn its case diameter is 44 millimetres it is equipped with valjoux 7750 automtic calibre that performs 28 800 vibrations per hour and has 26 bearing jewels sinns tegiment technology is used to make the case extra resilient a dehumidifying capsule protects the dial from fogging another amazing characteristic is the extreme protection from magnetic fields 900 pilot s has other useful features like a