Teachado - Portable Real Borosilicate Glass Water Tea Bottle Travel Mug with Nylon Sleeve with/without Tea Infuser (550ML with Tea Infuser, Grey) The body is made of high quality heat-resistant borosilicate glass and is not easy to burst due to the high or low temperature Cap is made of high quality stainless steel, and seals are made of food grade silicone, safe and sanitary. For the nylon outer cover, it provides a comfortable feeling and against hot. It makes easier to grip against falling off and effective protect glass body from damage. On-the-go water/tea mug lets you brew and enjoy hot beverages on the go Licensed trademarks of WSWS LLC