Abstract: A protective cap for fastener heads includes a preformed member formed of a naturally tacky compound of unvulcanized butyl rubber, a reinforcing layer of a non-woven polyester fabric, and a silicone-coated polyethylene release liner. The preformed member has a dome-shaped central portion and a surrounding generally flat annular flange. The reinforcing layer of the polyester fabric is disposed over a top surface of the preformed member to form a homogeneous cap construction, and the release liner covers the tacky bottom surface of the preformed member to prevent the cap from adhering to surfaces until ready for use. A plurality of the protective caps are formed in a manipulatable sheet unit and are maintained thereon by the natural tackiness of the unvulcanized butyl rubber compound.