1. [PREMIUM Material]The inner wall is made of 304 grade food grade stainless steel and the outer case is made of high quality 304 stainless steel.They also have the silicone bottom which is designed to prevent them from sliding and spilling. Other parts of these Travel mugs are made of BPA- PP materials ,food grade silica gels and Co-polyester plastic that make them Safe and Healthy to use. 2. [KEEP TEMPERATURE]Featured dual walls, premium coated copper on the exterior of the inner wall. High performance temperature retention, keep liquid hot up to 12 hrs and cold up to 12 hrs. 3. [PERFECT DESIGN]Steel flask is designed to reduce spills and sloshing. The bottle flask is leak proof and in the bag while on the go. 17oz / 500ml water bottle fit in most cupholders and easily fit in a bag to travel. 4. [EASY TO CLEAN]The inside of the lid is embedded with PP leak-proof silicone ring. Simple structure, washable with a spout removed,The cup mouth is smooth, it will not cut lips, the cup has large diameter, It has detachable filter net, can filter the residue such as tea. The bottom of the cup is made of non-slip material, which is not easy to slip off and is durable.