The invention relates to a comb (100) for being attached to a hair-cutting device (115). The comb includes two surfaces (103, 104) to be in contact with the skin of the user. Each surface includes a slot (105, 106) for attaching the comb to the hair-cutting device, and both surfaces have a common edge (107). When the hair-cutting device is attached to the slot of the first surface, the second surface is in contact with the skin, and when the hair-cutting device is attached to the slot of the second surface, the first surface is in contact with the skin. An asymmetric arrangement of the two slots allows for two cutting lengths of hair with one double-sided comb.