Surgical tool for use in guided surgery having a distal end portion having a functional element, a shank on the opposite end of the tool, and a substantially circular cylindrical guide portion. The guide portion is located between the functional element and the shank and has at least one visual marker. The at least one marker has at least one recess which is finite in the circumferential direction such that, at the axial location of the recess a section of guide portion having outer radius r is maintained.
