A base unit for a road stud is provided. In one embodiment, the base unit is made of plastic and has a recess with a plurality of projections. The projections extend over the floor of the recess for retaining a resilient insert within the recess. The base unit comprises a first portion representing the body of the base unit, and one or more additional portions fitted to said first portion, for example by adhesive bonding. Each of said projections may be formed from one or more planar elements. The base unit further has a front portion, a back portion, and opposing side walls, wherein the recess is located between the front and back portion and the opposing side walls. The underside of the front and back portions is provided with ribbing for transverse strengthening. A cavity is formed in the underside of each of the opposing side walls. A colourant may be added to the plastic of the base unit in order to colour the base unit, for example to match the colour of reflectors provided in the insert. The top surface of the base unit may be provided with an anti-skid pattern.