The part is then expanded and cooled while that expanded state. The result is a part that “wants” to contract to its original form when heat is applied. Forgaes and Dobo have studied the forces which are present during the “shrinking” of such a material. They have indentified two forces which are acting during the heat shrink process. The force which causes shrinking is identified as a function of elastomeric modulus and caused by the stretching of the material while the “holding” force is a function of crystallini and is a function of thermal contraction(2). The work goes on to show that the retractive force is a function of increasing crosslink density and extension, The holding force was observed to be essentially independent of crosslink density but was proportional to crystallinity and inversily proportional to temperature.