The Crablock is a symmetrical unit, this in contrast to the units that have been applied most in the past. Essentially, this is the main difference. All other units have six “obstacles” that insure interlocking, but they are not symmetrical. All those units are placed randomly in a certain way with more or less contacts to neighbouring units. A symmetrical unit may give the opportunity to place the units in a more or less rectangular pattern. This may ease the construction requirements. It may also have influence on stability, where the expectation is that it could be more stable than a random placement. Uniform placement may, however, increase the packing density (number of units per square meter) and/or wave overtopping. But at least one can say that the Crablock can distinguish itself from the well-known units by the symmetrical shape. The main objectives of this report are: 1) outline the recommendations for a fast and efficient approach to come to a design guidance; 2) establish what design parameters are most important for the new single layer armour unit investigation, such as the placing pattern, the crest height, the settlement, etc. 3) identify what kind of tests should be done for Crablock in a wave flume.