The Siliskin Sippy Top is a silicone top that stretches over and grips the top of a glass while air suction keeps the top in place. Added stretch and shock absorption bands give any glass extra protection. Add the Siliskin Sippy Top to the Siliskin Glass or any cup of your choice to make it an instant sippy. Comes in 2 pack. Dishwasher and microwave safe. Hypo-allergenic and BPA free.Silikids