Abstract: A tamper proof protective cover for cap screws. The cover is installed over either the head or nut, depending which is exposed to vandalism. There is a hemispherical or dome shaped surface with a slightly angled bottom to prevent getting a grip on the cover. A blind bore with a compression ring and gripping rings extending from the flat bottom surface into the blind bore. The protective cover is installed using a special tool by placing the bore over the head or nut of a cap screw and driving down on the head or nut. The gripping rings engage and either binds with or penetrates the edges of the head or nut.