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SF Siege Hooded Base Layer


Rated 5.00 out of 5 based on 15 customers 15 reviews
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  • UK DPD Next Day Delivery (Free Over £100)
  • Fast, Worldwide Delivery Available (Free over £300)
  • 30 Day no hassle exchange & Returns Policy

SF Siege hooded base layer - first line defence


Our battle-tested base layers have been developed with Polartec® Power Grid with a geometric construction which enhances moisture evaporation and supports thermal regulation.  The grid design creates open air channels that improve breathability and reduce fabric mass.  With a high neck collar, stiffened storm peak hood and integrated thumb loops for increased cold weather protection.

They’ve been submerged in ice cold waters on Op Skyefall, endured sub-zero conditions on Op Chamonix and resisted hurricane force winds on Mt Everest.  SIEGE against the elements … the first line of defence.


  • Polartec® Power Grid
  • Integrated thumb loops
  • Contrast upper left zip pocket
  • Stiffened storm peak
  • YKK half-zip with chin guard


Please refer to fabric care instructions for particular garment care. If you should have any further queries about the care of your garment please send us an email to [email protected]

Find out about the latest ThruDark product developments here




4-way stretch

4-way stretch

Quick Dry

Quick Dry

Thermo Regen

Thermo Regen



Dynamic Movement

Dynamic Movement



4-way stretch

4-way stretch

Quick Dry

Quick Dry

Thermo Regen

Thermo Regen



Dynamic Movement

Dynamic Movement

and fabrics

Cut from a different cloth




Polartec® Power Grid™ is the evolution of fleece fabric engineering. Our patented grid construction knit strengthens performance efficiency by increasing warmth and breathability, while also reducing fabric mass. These geometric patterns improve compressibility, wicking, and add technical style.

Learn More

SF Siege Base Layer


Louis : Height : 178cm Weight: 83kg Chest: 42" Waist 31" 31" - Wears size Large

Staz: Height : 173cm Weight: 76kg Chest: 38" Waist 28" 30" - Wears size Medium

Dylan Hartley : Height: 185cm Weight: 110kg Chest: 48" Waist: 38" 32" Wears size XXL

Foxy : Height: 188cm Weight: 100kg Chest: 44" Waist: 34" 34" Wears size L/XL

Matt : Height: 188cm Weight: 90kg Chest: 46" Waist: 34" 36" Wears size XL

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s m l xl xxl

Product reviews

Customer reviews and ratings

  1. Badgerov

    Wow just wow as soon as you feel the package and feel the weight I was blown away! Then when you open it and put it on you can just feel the amazing quality of this item looks great and feels amazing! For £125 this item is a steal it’s a must get for anyone that loves the Thrudark stuff!!!

  2. Belly

    My latest bit of kit from Thrudark and as expected is perfect and the timings was brilliant with this current weather has been worn as a base layer to block train in. Very happy.

  3. DT

    In keeping with Thrudark’s mission, this is another excellent product. The fitting size was as per the guidance and the Base Layer is a well thought through garment. Very pleased with this as it provides exactly the function intended and looks great. Worth the wait.

  4. Daren M

    FLAWLESS ! Well happy !

  5. guy williams

    Just arrived size medium 5ft 10 12 stone is spot on. Great stretch with room to move quality as ever . Quick service. Sits proudly with the recoil jacket and the heavy-duty pullover robust and light. Guy

  6. RA

    Screams quality *****

  7. Axel

    A very well throught out and designed product. Can be used as a base layer or a (very) active mid layer, depending on how you size it.

  8. Jeff

    This is the 6th item I have purchased from the Thrudark lads and as always, top notch quality.
    Great piece of kit with exceptional attention to detail and in my opinion an absolute steal for the money it cost.

  9. Paul

    Managed to get hold of two for me and the other half. Perfect as always. The quality never disappoints when ordering from Thrudark. Size wise I’m 46in chest and the xxl is perfect. Snug enough for a base layer but could be worn as a mid too. My missus has a small and is perfect. This with my phalanx is spot on 👍🏻🖤

  10. James Billingham

    Amazing product! Was able to get this on the launch day and was delivered 48hrs later. Tested out in -3 with just the base layer and my Zodiac and i was toasty. Cant wait to get this out more! 100% worth it!! Excellent quality! Excellent design! Thrudark Thru & Thru 👊🏻

  11. Russ Price

    Perfect piece of kit lads… door to door delivery to Australia in 5 days unprecedented also flawless perfection an exceptionally happy customer can’t thank you lads enough!! Russ from a land down under 🏴󠁧󠁢󠁷󠁬󠁳󠁿🇳🇿

  12. Joe

    Another amazing product from Thrudark. Great quality, great fit and great look. Buy it.

  13. Mr James Stirling.

    Received the SF ( Siege hooded Base layer) on the Fri 11th of Feb 21. Have worn this Base layer on its own. outside on cool windy day and I felt so warm & Comfortable you only realise your wearing it by what it says on the tin. I highly recommend it as abit of kit to wear under a good quality waterproof jacket in any harsh weather Conditions you will definitely feel the benefits. Once again money Well Spent. Thanks again lads from Thrudark with their Expert & professional impute in this Exceptional kit. Once again Mr James Stirling Leeds UK.

  14. Ricky Allan

    Another Quality product, keep knocking it out the park

  15. Barry

    I’d had my eye on the SF Siege since it was mooted in the development section of the website a few months back. My wait was entirely worth it….not that I expected any less from Thrudark who’s kit can only be described as phenomenal!
    Had to size down to a Medium from my original choice of Large but brilliant customer service saw it exchanged in a flash.
    The quality is amazing and the fabrics used, and construction of the SF Siege are exceptional. Really looking forward to testing it properly on a few Munro’s! Cheers Thrudark….from one delighted customer!

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