Yes it can be confusing, eapecially for a beginer. There are different types of rubber, silicone, urathane etc., that are use for different types of molds or what you are making in the mold. Then there are different shores, hardness (meaning- very soft & flexibal or hard & stiff). Then there are different tensil strengths, tear strenths, how tough the rubber is. If you would like more info, I can point you to some very good web sites, that helps explain all this better.