The traditional way of providing an edge to wet pour surfacing is using pre-cast concrete (pcc) edges. This presents a hard edge that the wet pour does not adhere to, so gaps can form later between the surface and the edge. These edgess are time consuming to install and make it difficult to create a smooth curve. Where wet pour is used as a safer surface, the introduction of hard edges, such as the pcc, creates a hazard.

An alternative method of providing an edge is to use timber gravel boards, which is relatively quick to install. The wet pour does not bind to this. Although easier to create curves, joints in the timber are often unsightly and a weak point.

The Cap Kerb has been designed by Star Rubber Environmental Ltd, to fit over a timber gravel board, providing easy installation. The Cap Kerb provides an ideal surface for the rubber surface to adhere to (hence reducing shrinkage). It also hides joints and saw cuts where the timber is used to create an arc and ultimately creating a safer edge finish to the surface.