Product information: Inner liner material: 316 stainless steel Features: thickened, for home use, portable, heat‑retaining, leak‑proof, customizable, cold‑retaining, tea‑water separation, splash‑proof Insulation performance: 6–12 hours Outer shell material: 201 stainless steel Style: with carrying strap, car cup, with straw, straight‑wall design, with tea infuser lid Material: 304 inside, 201 outside