Clear plasticizer which is used as a softener for the PMC series materials. In general this material does not change the A to B ratio for these elastomers. SO-FLEX™ II is a phthalate free softening agent that will lower the cured durometer of a variety of Smooth-On flexible polyurethane products. The following charts indicate the effect SO-FLEX™ II has on fully cured (7 days) PMC™-121/50, Vytaflex™ 30 and Reoflex™ 20 urethane rubbers when added as a percentage of the total mix.