These are Jed Lind double-wall vacuum bottles.
They are made of stainless steel inside and out.
The double-wall vacuum insulation keeps beverages hot or cold for over 8 hours, potentially up to 12-24 hours.
They come in various capacities, commonly including 500ml, 750ml, 1000ml, and 1500ml sizes.
The bottles are leak-proof, portable, and suitable for travel, camping, or daily use.