In order to evaluate design parameters of a new single-layer concrete armor unit-Crablock，which has been applied to a breakwater project in the Middle East，this paper analyzes previous physical model test results and compares main parameters of Crablock with those of 4 extensively used units，i.e. AccropodeTM，AccropodeTM II，Core-Loc and Xbloc. The results show that：1）The stability number of Crablock Ns ranges from 2.8 to 3.3，corresponding to KD value of 16 to 27，which has a better stability than the above 4 units. 2）The uniform rectangular placement pattern is recommended for Crablock，which differs from the random pattern of the above 4 units. 3）A smaller underlayer of 1/25 armor weight is proposed for Crablock，which is also different from the general underlayer of 1/10 of the above 4 units weight. 4）The overtopping roughness factor is not defined in the physical model test，but a value larger than 0.45 is verified. The actual wave overtopping shall be in accordance with the result from the physical model test.