Editor’s Note: There is an upgraded product available from this manufacturer and our buy button link will take you to it. We will fully evaluate and reflect this additional information when we next update the Thermoses review.
As a low-end model, the Isosteel Double Walled Slimline Vacuum Flask covers the basics but doesn't offer any outstanding features. It has a fairly generous capacity and is suitable for hot or cold beverages.
With a capacity of 25 ounces, this vacuum flask is suitable for work, the commute, hiking or picnics. Unfortunately, although it is big enough to provide refreshment for two people, it only comes with one cup, so you'll have to bring another if you plan to share. The cup doesn't have a handle and doubles as the top of the flask. When empty, it weighs 18 ounces so, once you add 25 ounces of liquid, the flask is rather heavy, which is an important consideration if you plan to walk with it all day. The weight means this model isn't the best thermos for carrying on the daily commute or while working out.
This thermos has a double-walled stainless steel construction and uses vacuum insulation. Although the manufacturer claims that this model keeps hot drinks warm and cold drinks cool, it doesn't specify for what length of time, so it's a case of trial and error. This model doesn't feature a mixing ball, so certain beverages may separate when kept in the flask for long periods. While suitable for many drinks, this thermos is not suitable for particularly thick liquids or soups. This is due to the quick-stop pour spout, which is too narrow to allow dense liquids through. The quick-stop feature is beneficial in that it minimizes spills and allows for quick and easy one-handed pouring.
The stainless steel exterior of this thermos is easy to clean and has a pleasing modern aesthetic. However, it is slippery when wet, particularly when you're wearing gloves, so would benefit from a contoured shape or the presence of a handle or a rubber grip featured on some other thermoses. The thermos is slimline, with a slightly tapered design, and fits neatly into a bag or picnic basket. The tight stopper limits the risk of leaks, as long as you screw it down properly, so you can lay the flask on its side when full.
For simplicity and ease of use, the Isosteel Double Walled Slimline Vacuum Flask offers good value at a low price point. Disappointingly, this thermos is heavy, and the slim design and stainless steel exterior make it slippery and difficult to hold when wet. As it is not suitable for particularly thick liquids, it lacks versatility.