Abstract: A corrosion protection cap for clamping onto a polygonal wheel nut, having a cylindrical casing which engages over the polygonal wheel nut, and having groove profiles formed in the web of a spring ring, which are open toward the casing axis and of which the vertices in each case correspond to the corners of the polygonal nut profile and the distance of the vertices from the casing axis is slightly less than the radial distance of each corner of the polygonal nut profile from the casing axis. The technical problem is a corrosion protection cap which can be clamped and detached virtually effortlessly by manual actuation and which moreover has a high pull-off force. The spring ring (10) seated in the cylindrical casing (2) has radially inwardly protruding webs (14) with said groove profiles, and the webs (14) are inclined in the radial direction toward the top wall (5) of the corrosion protection cap (1).