downwardly rather than upwardly as illustrated in fig2 a which is a generally graphical representation plotting force exerted by the spring shown in fig2 versus u201c l u201d the spring provides a decreasing force as it is retracted with regard to the spring depicted in fig2 this spring which is somewhat similar to the spring configuration shown in fig1 of the drawings achieves varying cross sectional mass by a constant force spring that has been modified to exhibit varying width along its length and also to exhibit a plurality of areas of reduced width along its length as illustrated in fig2 a of the drawings as this spring rolls up from the extended position shown in fig2 it will provide gradually less force followed by a non linear reduction in force at the area designated in fig2 as 60 followed again by a non linear increase in force followed by a non linear reduction in force at the area designated in fig2 as 60 a and finally at the point at which it is almost completely retracted once again exhibits a gradually decreasing force referring next to fig2 of the drawings the spring there depicted which is somewhat similar to the spring configuration shown in fig2 of the drawings achieves varying cross sectional mass by a constant force spring that has also been modified to exhibit varying width along its length and also to exhibit a plurality of areas of reduced width along its length however as illustrated in fig2 a of the drawings as this spring rolls up from the extended position shown in fig2 it will provide gradually increased force followed by a non linear decrease in force at the area designated in fig2 as.