Abstract: A beam- or truss-like reinforced concrete unit to inhibit the erosion of shorelines, sand beaches and river banks by the retardation and diversion of flow across them, intended to be placed on the bottom at right angles to the flow of sand-laden water, without being fastened down. Transverse passages formed by lower chord, upper chord and diagonal members allow water to flow horizontally through the unit, but cause sand to drop out. Diagonal structural members provide great stiffness and strength, despite the presence of the open passages. To increase the fallout of sand, the passages are in two groups which meet at the centerplane of the unit, out of registry with each other, so that each group of passages is obstructed by the diagonal members which form the other group.