A two speed shift mechanism for a belt drive that includes a rotatable shaft with a first pulley, and a tube concentric with the shaft and rotatable therearound. More particularly, this invention relates to intraocular lenses that have the ability to alter the light refractive power in response to changes in the tension of the ciliary muscle or ciliary body of the eye or any other accommodative forces. 05-10 m and a fibrous inorganic filler, excluding glass fiber, having a fiber diameter of 0.