Some of the reasons why we prefer the Elastomer over Silicone are based on improved manufacturing practices that are possible with TPE. Recently independent studies on menstrual cups by a microbial expert in France have shown that cups made from TPE are less likely to harbor harmful bacteria than menstrual cups made from silicone. Many products that have been made ​​previously out of rubber or silicone, are now made out ​​of TPE. TPE has a lower incidence of causing an allergic reaction than silicone. TPE is also a very pliable material that readily conforms to its surroundings for an even more custom feel for the wearer. You may find that over time your TPE cup becomes a bit more oval in shape after adjusting to its wearer’s shape. This is nothing to worry about. The cup will again conform to your shape the next time you wear it. If you ever would like to return the cup to its original completely round shape, simply boil the cup in hot water.