This all silicone 12 oz cup is 100% European grade silicone with an embedded stainless steel ring. It won’t collapse when gripped. The all silicone straw top and straw inserts for a tight fit and all parts are dishwasher and microwave safe. Silicone cup that holds it's shape, no collapsing mouth. Silicone top inserts for a tight fit. Can be boiled to sterilize. 100% silicone and 100% stainless steel. Dishwasher and microwave safe.