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SF Siege Hooded Base Layer


Rated 4.93 out of 5 based on 15 customers 15 reviews
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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

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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
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Toughened with a specially engineered Swiss Schoeller® fabric containing ceramic coating technology. When knitted fabrics are subjected to serious abrasion, for example in cycling, the new Schoeller® ceramic coating technology is the ideal solution. The unique ceramic coating offers reliable protection and a high level of comfort even in extremely elastic knitted fabrics. This innovative coating technique involves binding fine ceramic particles firmly onto the textiles, providing protection from excessive wear and tear as well as pilling. 4-way stretch, abrasion resistance, breathable, reflective and hydrophilic.


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. Mark F

    I have bought a number of great items from Thrudark, but this has to rate as one of my favourites. Excellent as a base layer or even worn alone. It is very well made and well worth the cost.

  2. Benjamin Barker

    Since the first sneak peak I knew I had to get one, I missed the first batch because I had no phone, so I had to wait far too long, top quality base layer. Thrudark have alot of decent kit but this particular item is proper ally. Comfortable, great fit and looks mega.

  3. Cris

    Likewise I have a number of items from Thrudark. This garment is perfect as the designed base layer but great for wearing alone. The cut,fit and quality is typically Thrudark…. awesome.

  4. Russ Price

    I’ve purchased quite a few products from these legends and they are all on point !! The base layer is like it’s not even on was recently in Far north Australia wet and cold and warm all in the same day . epic product thanks guys

  5. Chris Akass

    This is my first purchase from Thrudark. What can I say…I’m now a fan! The product is well made its so comfortable it’s like your not even wearing it but it’s also like being wrapped up in a duvet. I have worn it on a cold day underneath a puffa and its so warm. I think one of many more purchases.

  6. John E

    3rd purchase from the team, top quality as eexpected. Worn as a base or on its own and as previous reviews comfortable and a great fit..Looking forward to my next purchase👍

  7. Jason

    This is simply outstanding! Looks incredible and performs brilliants under a puffer or just by itself over a T-shirt. Walking, running, hiking! Awesome!

  8. Ernest Kim

    The SF Siege is my favourite all-purpose gear from ThruDark. I wear it to parties, hiking, the corporate office and to sleep. I’ve worn it in 5C freezing cold, 22 knot winds on a boat, and warm 25C going for a neighbourhood run. Whoever designed it is a genius.

  9. Scott Davidson

    First off, this is so much more than just a base layer.

    It’s perfect underneath the SF Raid, but I wear it regularly as an outer top as well.

    The quality of the materials are awesome and it looks brilliant on. So many neat little touches like the chest zip and thumb loops.

    You can literally see the attention to detail that has been put into this item and it’s not just a generic top that so many of the other brands churn out.

    Yet another cracking piece of kit from Thrudark.


  10. Andrew Cowderoy

    I bought SF Siege Hooded Base mid winter in Scotland and I didn’t want to take it or, soft, warm idea for a hike, winter or winter run. Ultra breathable, light wait, looks shit hot and keeps you warm. I took it up Ben Lomond the other day, through it on at the top to take the chill of and was the perfect go to. Will buy more for this winter.

  11. Ant

    Just taken delivery of the SF Siege Hooded Base Layer. Only tried it indoors so far but its warmth is instant and impressive. Look and feel are excellent although I’m not sure about the hood which might be an acquired taste. I might appreciate it more in a few months! If there was a version of this item with a conventional jacket style collar I think it would be perfect for everyday use through the winter and not just for hiking in the wilds.

  12. Andrew

    With winter approaching I was looking for a base layer. Wasn’t sure what to expect as the price point was higher than some of my other base layers. Have to say now it’s arrived I’m glad I invested.

    It’s a very good cross over garment – a base layer for extreme cold or on its own for changing conditions. Has a nice length so can be tucked in or worn loose. A few usual nice touches and usual attention to detail. The fact the peak on the hood can be folded flush to the hood is a nice touch when wearing a helmet or just having it out of the way.

    Would recommend and can see this being a stable part of my autumn/winter kit list.

  13. Robbie Draper

    This item is the perfect base layer, or even a stand alone hoody/top. I’ve worn for going to and from the gym, cycling, running and walking. A fantastic addition to the wardrobe. Oh, and it also looks cool as f……

  14. Kevin Harrin

    Going to repeat what has already been said. Have several items from Thrudark all are top quality items but I think this is my favourite. Really comfortable and warm, and looks the nuts. If your in two minds wether to buy or not, just do it, you won’t regret it.

  15. shaun clay

    Hi my 1st Thrudark purchase perfect fit excellent & quality
    to early to test although won’t be long as autumn has arrived i will be wearing this at work in the winter and spending 2 weeks in snowdon in december. also going to order the SF raid jacket . great products guys thanks

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