involve placing one or various blocks of an elastomer material between the metal piece or pieces of a retention or tension device irrespective of whether these are joined to these or not and which consists of a structural material or a matrix of an elastic type material preferably synthetic which contains in its mass a large quantity of small cavities or closed cells generally separated from each other and full of a gas susceptible to compression when a compression of the elastomer block takes place and which show a minimum deformation in directions that are traversal to the force on the elastomer this invention since it introduces blocks of cellular material with a matrix or structural material of a synthetic and elastic type and multiple chambers full of a gas eliminates the disadvantages of the compact rubber type elastomers that are normally used and it preserves the main advantages that these offer the application of this invention in locking systems in the form of a block between two sandwich type metal support pieces or as a tensor or retainer allows these elements to absorb major forces offering a very reduced transverse expansion and a greater resistance to the flexion torsion and practically eliminating the possibility of breakage or loss of the lock element likewise a greater level of resistance is achieved upon ageing and a better response to the deformation forces at the same time the mounting is easier since the lock elements for example the pins offer a greater elastic behaviour compared to those that currently implement.