A breakwater structure is designed to absorb the energy of the waves that hit it either by using mass (e.g., with caissons) or by using a revetment slope (e.g. with rock or concrete armour units).
A breakwater structure is designed to absorb the energy of the waves (e.g. with rock or concrete armour units). These waves hit it either by or by. These waves were using a revetment slope. These waves were using mass (e.g.) or by using a revetment slope. This was with caissons.