Methods, systems, software arrangements and storage medium for measuring the magnetic field correlation function, and more particularly, to methods for measuring the magnetic field correlation function utilizing asymmetric spin echoes. More specifically the suspension tuning device generally comprises an upper plate, two lower plates and a strut mounting plate. A method of optical bonding is further provided. Thus, when the key is released, the contact between the side surface of the protrusion and the contact portions prevents the key from rotating before the hammer, thereby preventing the protrusion from departing from the sliding surface and suppressing the generation of noise that occurs when the protrusion falls on the sliding surface.