ASTM D 5672 (D-5672) deflection IFD method is recommended for production screening and quality control on full size cushions only. Applicable cushion thicknesses to be tested by this test method are only those listed in this test method. Further research and development are required before this test method will be applicable to other cushion thicknesses. This test method is designed to give a value approximating the 25 % IFD on a 100-mm (4-in.) thick piece of foam when the actual specimen thickness tested is within the ranges listed in the test method. In case of disagreement, the referee method is the IFD procedure in Test Methods D 3574, Test B1. The user of this test method shall establish the correlation between this test method and the referee method.