I was in menswear for many years and know well the efficacy of using shoe trees.  Shoes will hold their shape better and the shoes will last longer when shoe trees are used.  These shoe trees by Stratton are quality trees made of cedar that will wick moisture quickly from shoes and leave a pleasant cedar smell.  I ordered a medium for my size 10 shoes and they fit snugly which they should do if they are going to keep the shoe shaped properly.