Abstract: An umbrella, having a cover stretched over a plastic folding radial frame which comprises upper, intermediate and lower nest plates respectively mounted on a main shaft for securing a plurality of ribs. The nest plates are identical in structure, each comprised an upper circular member having a plurality of pawls and retaining holes at the bottom respectively engaged with a plurality of retaining holes and pawls on the top of a lower circular member for securing the ribs. The cover comprises a plurality of fastening caps at the corners around its periphery and a plurality of snap fastening elements on each radial line thereof for securing the ribs. Because all the parts are made of plastic material, the umbrella is not electrically conductive and can protect against lightning.