Hair-cutting appliance comprising at least 19 hair-cutting units each comprising a guard element and a rotatably arranged hair-cutting element having at least one hair-cutting edge , wherein the guard element is configured as a guard for the hair-cutting element and arranged in the hair-cutting unit to cover the hair-cutting element , wherein the guard element is generally cup-shaped and comprises a base and an annular wall extending from the base , wherein a diameter of the base is in a range of 7 mm to 13 mm, wherein the base includes a shaving track which: - is annular about a central axis of the guard element ; - is provided with a plurality of hair-entry slits ; - has an inner surface at a side facing the hair-cutting element in the hair-cutting unit , and an outer surface at an opposite side; and - has a hair-cutting portion which is designed to cover the hair-cutting element in the hair-cutting unit at the position of an annular hair-cutting track followed by the at least one hair-cutting edge of the hair-cutting element during rotation of the hair-cutting element ; characterized in that , in at least the hair-cutting portion of the shaving track and as seen in a longitudinal section of the guard element including the central axis , at either side of the central axis both the inner surface and the outer surface of the shaving track have: - a conical shape relative to the central axis with a similar slanting orientation relative to the central axis ; and - a straight outline, wherein the inner surface of the shaving track is oriented relative to the central axis at an inclination angle (α i ) which is in a range of 45° to 78°. wherein the guard element is configured as a guard for the hair-cutting element and arranged in the hair-cutting unit to cover the hair-cutting element , wherein the guard element is generally cup-shaped and comprises a base and an annular wall extending from the base , wherein a diameter of the base is in a range of 7 mm to 13 mm, wherein the base includes a shaving track which: - is annular about a central axis of the guard element ; - is provided with a plurality of hair-entry slits ; - has an inner surface at a side facing the hair-cutting element in the hair-cutting unit , and an outer surface at an opposite side; and - has a hair-cutting portion which is designed to cover the hair-cutting element in the hair-cutting unit at the position of an annular hair-cutting track followed by the at least one hair-cutting edge of the hair-cutting element during rotation of the hair-cutting element ; - is annular about a central axis of the guard element ; - is provided with a plurality of hair-entry slits ; - has an inner surface at a side facing the hair-cutting element in the hair-cutting unit , and an outer surface at an opposite side; and - has a hair-cutting portion which is designed to cover the hair-cutting element in the hair-cutting unit at the position of an annular hair-cutting track followed by the at least one hair-cutting edge of the hair-cutting element during rotation of the hair-cutting element ; characterized in that , in at least the hair-cutting portion of the shaving track and as seen in a longitudinal section of the guard element including the central axis , at either side of the central axis both the inner surface and the outer surface of the shaving track have: - a conical shape relative to the central axis with a similar slanting orientation relative to the central axis ; and - a straight outline, wherein the inner surface of the shaving track is oriented relative to the central axis at an inclination angle (α i ) which is in a range of 45° to 78°. - a conical shape relative to the central axis with a similar slanting orientation relative to the central axis ; and - a straight outline, wherein the inner surface of the shaving track is oriented relative to the central axis at an inclination angle (α i ) which is in a range of 45° to 78°. <EOS>