Many different approaches have been tried to achieve enough rigidity and lightness to counter the distorting effects of cone 'break up', when the outer portion of a cone vibrates out of phase with the centre at higher frequencies. The trouble is, stiff light structures such as metal cones usually exhibit high 'Q' resonances, while the rigidity of Kevlar and carbon-fibre cones varies with the direction of weave, generating strong bell modes in the break-up pattern.

Celestion engineers came up with an ingenious solution, using an inherently stable arch shape, with the lines of stress contained within the material so the shape is maintained by the strength of the material in compression or tension rather than its bending stiffness. The material they chose is polypropylene loaded with flaked mica. Because mica flakes align in the direction of flow during the injection moulding process, they stiffen the cone evenly in the plane of the surface, as well as damping high frequency resonances by shear between individual flakes.