TempShield double-wall vacuum insulation. Leakproof-Flex Sip Lid is leakproof when closed. Made with 18/8 pro-grade stainless steel to ensure durability pure taste and no flavor transfer. Color Last powder coat is dishwasher safe keeping your product slip-free and colorful. Fits most cupholders. BPA-Free & Toxin-Free. Dishwasher safe.