Tool with protruding structure

A tool for a power tool, the tool having a longitudinal axis (L) and comprising a working section and a shaft with a connection end for connecting the tool to a tool holder of the power tool, wherein the shaft comprises at least one protruding structure protruding from the shaft the shaft having a surface and two halves (A, B) wherein at least within one of two halves (A, B) of the protruding structure which are separated from each other by a plane perpendicular to the longitudinal axis (L), the surface of the protruding structure has a finite gradient along a direction parallel to the longitudinal axis (L), and within the half A the surface of the protruding structure comprises several sections with different radii of curvature, wherein an angle (alpha) between a tangent through a point (P) of the surface of the protruding structure and the longitudinal axis (L) is an acute angle less than 90° in relation to the longitudinal axis (L).