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Published Jan. 19, 2021

Though often associated with civilian wilderness excursions, thermoses actually have a proud military history dating back almost a century. The vacuum technology was developed by Scottish scientist Sir James Dewar who, instead of patenting the invention, enabled companies to advance it. Thermos, the namesake of this article, originated as three independent companies: one in England, one in Canada, and one in the United States. While the First World War marked a downturn in production, the company kicked back into gear in 1931. During World War II, roughly 98 percent of the American Thermos company’s products were put towards military usage. After that, the Thermoses became popular amongst military personnel and civilians alike for keeping food and drink warm both on the battlefield and at home.

In 1963, the phrase ‘thermos’ became a general term for all vacuum flasks, and to this day, they are found everywhere from lunch kits to the battlefield. But, without a standard-issue flask, it can be tricky to pin down a good option. To help, we’ve curated a list of the best thermoses on the market, along with some tips on finding the right fit.

Want something that represents the classic thermos that got countless troops through the challenges of the battlefield? Check out the Thermos Stainless King Beverage Bottle for its iconic design and high-performance value. The bottle is able to hold up to 40 ounces of fluid, whether hot or cold. In keeping with thermos expectations, the vacuum technology effectively keeps fluids at the proper temperature for up to 24 hours. Whether the contents are hot or cold, the exterior remains safe to the touch. The metal construction prevents the risk of cracks and damage should you drop your thermos, and a prominent handle on the side lets you tow it wherever you go. The lid doubles as a cup, letting you drink comfortably even when dealing with challenging conditions.

If the history of vacuum flasks is any indication, thermoses evolve with time. The Contigo Stainless Steel Travel Mug showcases the modern twist on traditional thermos tech. With a sleek design and sturdy exterior, this thermos fits just about anywhere. It holds 14 ounces of fluid and is meant to fit into the slot of a single-serve coffee maker. The mug is sturdy and well-balanced, and thanks to the metal exterior it won’t crack or break if dropped. Though it doesn’t have a handle, the thermos is slim enough to easily grip on the go. Performance-wise, it keeps your hot fluids warm for up to five hours, while cold contents remain icy for up to 19 hours. For those seeking an option for the field, you can get this bad boy in a range of camouflage tones. Affordably priced and effective, the powerful seal and safe materials make this a worthy option.

If you want a vacuum flask that could survive the trenches, then the Stanley Classic Vacuum Insulated Bottle is worth looking into. It features metal construction with powerful insulation that holds the temperature of its contents steady for up to 24 hours. With a handle at the side and a lid doubling as a serving container, it makes eating and drinking easy under challenging conditions. The thermos holds a full quart of fluid, though you can get it in larger sizes for longer excursions. With a wide mouth for quick sipping and a powerful seal, this thermos is reliable in outdoor conditions. Since it is made out of corrosion-resistant materials, you can use it on an ongoing basis without compromising its utility. Lightweight yet sturdy, this thermos can withstand the elements with ease.

Simple and understated, the Fijoo Stainless Steel Coffee Thermos is effective everywhere from the workplace to a camping trip. Using the same technology that kept soup warm for soldiers during World War II, this thermos keeps fluids at prime temperature for up to eight hours. Featuring an added lining made of copper, it enhances the strength of the shell while preventing your hands from getting burned. The sleek design comes without handles, making it easy to grip. The twist-off lid prevents leaks and spills through effective sealing. With a metal structure, even if you drop it or need to toss it aside in an emergency, the thermos will function just as well. Ideal for travel and spending time outdoors during training, this thermos is a solid choice.

Military work is physically demanding, so you need a thermos that can keep up with the demand. The Iron Flask Sports Water Bottle is a good candidate for those looking to keep fluids cold during strenuous exercise. It is made using high-end vacuum technology which, when paired with the stainless steel shell, offers a high level of durability. The bottle features a compact handle for easy transportation and incorporates a trio of lids. One uses a carabiner and straw for easy access to fluids (without risking them getting warm). The flip lid and stainless steel twist-on lid also facilitate temperature control so the bottle effectively keeps contents cold for up to 24 hours and fluid warm for up to 12 hours. Lightweight and easy to travel with, this sleek thermos makes training that much easier.

Related: 7 coffee accessories to help you brew like a barista

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Over five years of product review experience has given me unique insight into tactical supplies, survival gear, and other essentials. Using my background in journalism and science education, I objectively assess products and have curated a reputation of reliability. By using personal experience paired with expert information, I supply reviews readers trust. My work can be found on Car Bibles, Narcity Media, and The Drive. Some of my recent pieces for Task and Purpose are reviews of tactical backpacks and gloves, as well as hydration packs.

Types of thermoses

  • Multipurpose: The highest utility selections feature the ability to support both hot and cold contents. This type of thermos features substantial insulation inside of the shell. The vacuum technology can keep contents at the proper temperature for up to 24 hours. True multipurpose thermoses are able to hold both drinks and soup. While these thermoses are powerful, they tend to be bulkier and much heavier than their more basic counterparts. 
  • Hot content: The phrase thermos was adopted in reference to the Greek word for heat. Though originally the vacuum packaging was used for military-focused purposes, it became popular among civilians as a coffee thermos. These containers are slimmer than their multipurpose counterparts and are usually designed to fit beneath a coffee maker. A downside of this type is that they usually must be hand washed to prevent heat damage to the insulation. 
  • Cold content: Often used for exercise in hot climates, cold content thermoses are options that keep fluids cold longer than they retain heat. These are popular amongst runners or those undergoing outdoor training. It prevents the sun from heating up the fluid, making it easier to prevent heatstroke and dehydration. Most come with a carabiner to make it easier to hold the thermos while on the most. They are also fairly lightweight, adding ease to transportation.

Key features of thermoses

  • Outer shell: The outer shell of the thermos is an important feature. Usually made of metal (mainly stainless steel), you can also find shells that come with a layer of plastic. The most important part of this component is remaining cool to the touch, regardless of the contents. The outer shell must also resist damage from impact in case the thermos is dropped. 
  • Insulation: Perhaps the most necessary feature of any thermos is the insulation. Found between the outer and the inner shell, it is the vacuum technology that offers thermoses the heat-control properties for which they are famed. Basically, the technology sucks the air out of the flask, preventing any convection and keeping the contents at the proper temperature. The higher the quality of the insulative layer, the better the thermal control you get. 
  • Lid: The lid of a thermos is essential to seal in the contents. Original thermoses used a twist-off cap which, in most cases, doubled as a serving dish for soup or coffee. The main lid is usually metal, though modern thermoses feature a second lid to create a firm seal and decrease the risk of thermal convection. Open lids are where most heat (or cold) has a chance to escape, so it’s important that the lid is user-friendly so you can efficiently recap the thermos. 
  • Handle: Most heavy-duty thermoses have handles at the side. It enables you to carry the thermos with ease, even letting you attach it to your other gear. The handle is usually made out of a rubber or polymer strap, attaching via metal to the outer shell. While helpful during transportation, handles are the parts most likely to get damaged during use. Check for a high-quality handle with secure attachments to mitigate this risk. 

Benefits of thermoses

Unlike other bottles that lack a strong outer and inner shell, thermoses are tough against damage. Particularly those with a metal casing, thermoses won’t crack if they are dropped on hard ground. More importantly, thermoses are effective in all climates, functioning equally well whether you are exposed to the elements or drinking indoors. If you are battling the heat, the last thing you want is unseasonably warm fluid to rehydrate. A thermos preserves the cold of your drinks for as long as 24 hours, so you always have a pleasant drink on hand. Battling the cold is challenging, leading to the risk of hypothermia at worst and discomfort at best. Access to warm beverages is more than a comforting convenience, it is necessary to ensure health and safety in the field. Thermoses keep fluids warm for longer periods. The versatility of the thermos is highlighted by its proud military history and its continued use everywhere from camping to exercise. 

Thermos pricing

Usually, thermoses that run under $20 are lighter-duty, working better for either hot or cold beverages. Often, these thermoses support smaller fluid quantities. Most heavy-duty, multipurpose thermoses run upwards of $20. You can almost certainly find a large-quantity thermos in this range that is both durable and effective.

How we chose our top picks

Thermoses have an impressive military history, with almost all of the Thermos products going towards the US World War II effort. Tracking the progress of thermoses over time (including the decision to call all similar vacuum flasks by the same name), we saw the evolution of these important items. Identifying the modern types that are most useful in today’s world, we shortlisted the top options. Factoring in user feedback, the repute of the manufacturer, and the cost, we finalized our list of the best thermoses around. The result is a vacuum flask that will get you through any situation.

Related: 5 barware items for crafting the perfect old fashioned

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