Flexible closures and other flexible optical assemblies that are installed within a factory, or in the field, and then deployed using cable installation methods, wherein the flexible closures and assemblies have the ability to bend and twist without incurring physical damage to their structure, optical fibers and splices disposed within, and without significant attenuation in the optical fibers when exposed to conventional installation stresses. Flexible closures that replace conventional substantially rigid closures in order to facilitate pre-engineered and assembled distribution cable installation within an optical network, and the physical, bending and material properties of such closures, and methods of manufacturing and installing the same.