a spring loaded plunger which when unlocked will allow the plunger to compress u00bc u2033 therefore only allowing a compression of the chest of 1 u00be u2033 when locked the compression will be 2 u2033 locking the plunger can be done by rotation fasteners or any other means to stop it from compressing the compression can be done by springs compressible material or mechanically as illustrated in fig4 a the plunger 4 may have threads on the outside and house 5 springs 20 the ring 24 threads onto the plunger 4 with holes in it to allow the springs 20 to pass thru the platen 22 is captured by the ring 24 and has receptacles for the other end of the springs 20 when extended as shown the platen 22 can be compressed towards the plunger 4 by u00bc inch when forced against the body pushing thru the ring 24 when the ring 24 is threaded all the way onto the plunger 4 the platen 22 is drawn in u00bc u2033 to the plunger 4 and can no longer compress against the plunger 11 although several embodiments of the disclosure have been disclosed in the foregoing specification it is understood by those skilled in the art that many modifications and other embodiments of the.