Woodlore — School of Wilderness Bushcraft  

Thermos Ultimate Flask 900 ml


Thermos Ultimate Flask 900 ml


Brand: Thermos
Weight: 380 g         10 reviews
The Thermos Ultimate Flask is a premium flask from a range that is synonymous with quality, durability and heat retention. Founded in 1904, Thermos is the leading manufacturer worldwide of insulated food and beverage containers.

This hard-wearing flask will keep your hot drinks hot and your cold drinks cold, for 24 hours. It also features a unique, two part stopper for ultra smooth pouring and a larger capacity cup.

  • Thermos™ vacuum insulation technology for maximum temperature retention, hot or cold
  • Durable stainless steel interior and exterior
  • Cool to the touch with hot liquids, sweat-proof with cold
  • Protective silicone rings for ultimate durability
  • Two part stopper to smooth the flow of liquid
  • BPA Free
  • 5 year guarantee
  • Capacity: 900ml/0.9L
  • Dimensions: 30cm x 8cm (Height x Width)
  • Weight: 380g
  • Available in Charcoal and Matt Black


  Delivery in 1-2 days within the United Kingdom
  UK Orders placed before 2PM GMT will be dispatched the same working day
  Overseas delivery times will vary depending on the destination

Please note that our offices are closed at weekends, so any orders placed after 2PM GMT on a Friday will not be dispatched until the following Monday.

Orders with a total value over £300.00 will be dispatched free via a next day delivery service within the UK at no extra cost.

Please note that in some instances, orders for heavy items may take an extra day to arrive.

  Overseas deliveries
For overseas deliveries, please refer to the following estimated delivery times:

  • Europe: 3 - 5 working days
  • Rest of the world: 5 - 7 working days


A full refund or exchange will be given provided that the items have not been worn or used, and are returned to us within 30 days of purchase, together with all relative labels and packaging. You are responsible for the cost of returning items.

Please ensure that you include a copy of your invoice, along with an explanation of why you have returned your goods. If you wish to return your goods for any reason, please do so to the following address:

Woodlore Limited
PO Box 3
East Sussex
TN19 7ZE
United Kingdom

Product Reviews

Thermos Ultimate Flask 900 ml is rated 5/5 based on 10 customer reviews.

All of our product reviews are from customers with verified purchases.

Overall Rating:


  1 of 10

  A fine looking thermos indeed, even though I haven't used it yet, it looks very capable flask. The construction of the flask looks good and I look forward to giving you an updated review when I've tested it.  

  Mark Armley
12th January, 2022

Rated: 5/5

  2 of 10

  Sleek style and design and fits easily in all my bags. 900 ml is a great size and drinks remain hot. Easy pour stopper is ideal one small twist and your in, easy to clean. Other flasks I’ve had are like tanks, this one is not, and does a much better job. Great flask  

  Mike Bilton
30th June, 2021

Rated: 5/5

  3 of 10

  This is now the third we have bought as they are so good. Indestructible and excellent at keeping drinks hot for long days on the fells, kayaking, canoeing and open water swimming. The most efficient flasks available. Easy to clean thoroughly as the whole top unscrews. The only niggles are the silicon bands don't stay put, and if you damage the rubber seals, you have to replace the whole top assembly.  

  Bernard Green
24th December, 2020

Rated: 5/5

  4 of 10

  Bought this primarily for work use and it does a great job at keeping my tea hot all day. The screw cap is a simple design and easy to clean which much better than other stoppers with fancy pop up caps. Overall a robust quality flask that does a good job of keeping things hot. Backed by Woodlores quality service and prompt delivery.  

18th April, 2020

Rated: 5/5

  5 of 10

  This flask defies the laws of physics! I don't know how it's possible to keep drinks warm for 24 hours but this flask does it. Overall the size and shape allow it to fit in a small rucksack. The nozzle design is so easy to use I have poured coffee one handed. If you are looking for a new flask for whatever reason, this one may not be the cheapest but it is the best. I am considering buying another one of these.  

  Alan Todd
13th February, 2020

Rated: 5/5

  6 of 10

  I have had some flasks over the years but nothing compared to this one, just buy it - you will not be disappointed.  

21st April, 2019

Rated: 5/5

  7 of 10

  Since I got this I've been using it for going to work and also out door trips. I have to say I am super happy with this product. It is lightweight and keeps your drink at the right temperature for a really long time. I absolutely love this and I strongly recommend it.  

  Reza Etemad
27th November, 2018

Rated: 5/5

  8 of 10

  Excellent thermal insulation properties, clearly well made. We have three of these. Would consider something lighter, with similar robustness.  

  Angelo Sklinitzis
11th June, 2018

Rated: 4/5

  9 of 10

  A very well thought out flask. The 2 part stopper is far better than the push button types and they don't fill with gunk which can be hard to clean. Keeps my coffee pipping hot over 9 hrs while at work, even down to the last cup. Seems to be very robust, but only time will tell on that.  

  Leo Stringer
22nd May, 2018

Rated: 5/5

  10 of 10

  Only received today but initial impressions of this flask are extremely good. Feels solid and strong but it's very light, basically as light as a regular water bottle. Screw top lid is simple, secure and makes a good seal. Easy to pour and take apart. Plastic mug fits securely on the top and also nests in a Zebra stainless mug perfectly. As for holding hot liquid. I put boiling water inside at 11AM today, it's now 8:30PM with the water still at scalding, tea brewing, burn yourself hot temperature. I've never had a proper Thermos before and thought it would probably do a couple of hours on a hike, but it would easily hold hot water through the day for freeze dried meals in the evening or overnight for a coffee/hot wash in the morning without getting another fire going. A Thermos is perfect for hot drinks on the hills in winter but for this weight and size, I think it'll be coming on quite a few trips in summer too.  

  Rob Smith
28th April, 2018

Rated: 5/5

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