12 oz No Spill Sport Sipper with Soft Silicone Sipper cups have the soft silicone spout that is uniquely designed to prevent drips and spills. The unique soft silicone spout allows fluid out of spout with sucking action of child. The silicone spout closes when sucking action ceases, insuring a leak resistant cup, while being delicate and gentle to baby’s gums and emerging teeth.