Abstract: A display panel constructed from a plurality of similar panel members 10 having a cross-section shaped to provide an undercut recess 14, 16 extending throughout its length along at least one of its longitudinal edges. Each panel member has a formation 22, 26 along one longitudinal edge and a correspondingly shaped formation 22, 26, along another longitudinal edge, so that the panel member can form a tongue and groove joint with a similar panel member. The relationship between the undercut recess and the adjacent formation is such that when a joint with another panel member is effected the undercut recess remains open. Thus the panel members can be used to construct a slatted panel display system.