Energy conversion
Body heat is absorbed by the mineral matrix and re-emitted as FIR light in the 6–14 µm range.
Nanofibre K-Filters
Pack of 5
£10.50 GBP
Sale price
£10.50 GBP
Regular price
£15.00 GBP
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Nanofibre K-Filters
£10.50 GBP
Sale price
£10.50 GBP
Regular price
£15.00 GBP
K-Mask5
Express Next Day Available
Key Features
K-Filters:
- The Nanofibre K-Filter has a filtration rating of 99.6%* - effective for 200 hours before filter needs replacing.
- The K-Mask and K-Filters can be baked in the oven at 60 degrees, during their 200 hour period to kill all trapped bacteria and viruses, offering added security.
- The K-Filter is made from biocompatible hydrophobic material which is elastic and electrostatic, meaning they are highly breathable and flexible, and will not become wet with water vapour from breathing. This also reduces the carbon dioxide re-breathing occurrence.
- The K-Filters can be cut to size without damaging the technology, allowing you as a customer to either use it in your Infrared K-Mask or any other mask you own.
Description
Available individually or in 5 packs, 17% discount on 5 pack cost.
Using a triple sandwich layer, nanofibre combination, the K-Filters have been designed as a re-usable, world class filter that will protect you and those around you.
Layer 1: Nanofibres capture viruses, bacteria and pollutants via electrostatic attraction.
Layer 2: Activated carbon layer for environmental pollutants.
Layer 3: Nanofibres capture viruses, bacteria and pollutants via electrostatic attraction.
The filters have been independently tested to ASTM F2100, ASTM FT101 and EN 1486 standards, certifying the 99.6% filtration rating*. The K-Filter offer its protection for 200 hours and for particles as small as 0.03 microns. The effectiveness of the filtration level is due to this microscopic level of protection offered by the electrospun nanofibres, that ionically attract the particles before trapping them within the filter layers. To contextualise this, the Covid-19 virus has a particle micron size of 0.06-0.5 and bacteria has a particle size of 0.3 microns. Healthcare workers on the front line have so far been using N95 rated masks that have a particulate protection size of 0.3 microns; so the wearer can feel confident in their protection when using the K-Filter.
The nanofibres within the K-Filter are made from biocompatible hydrophobic material which are elastic and electrostatic, meaning they are highly breathable, flexible and will not become wet with water vapour from breathing. This also reduces the carbon dioxide re-breathing occurrence that is a problem among even medical grade respirators.
The K-Filters can be cut to size without damaging the technology, allowing you as a customer to either use it in your Infrared K-Mask or any other mask you own.
This is why the KYMIRA K-Filter has proven itself to be one of the most effective air filters in the world.
Best Use
Wear the K-Filter in the K-Mask for a perfect fit, or add the filter to any other mask with a filter pocket included.
Wear your mask with K-Filter whenever you are in public, or in large groups of people - to protect yourself, and those around you.
Change the filter for a fresh K-Filter replacement at least every 200 hours, for continued 99.6%* protection from viruses, bacteria and environmental pollutants.
The K-Masks and K-Filters can be baked in the oven at 60 degrees, and this will ensure that all trapped virus and bacteria particles are killed.
Fabric & Care
The Nanofibre K-Filter offers the wearer 200 hours of viral, bacterial and pollutant filtration protection. Once this time period is completed, the filter can be replaced with a fresh filter, and the protection will continue.
The K-Masks and K-Filters can also be cleaned and reused during this 200 hour period. The masks and filters can be baked in the oven at 60 degrees centigrade and this will ensure that all trapped virus and bacteria particles are killed.
Reviews
Why IR50? Our Most Advanced Recovery Technology
- Boosts circulation to deliver oxygen and nutrients where your muscles need them most.
- Accelerates lactic‑acid removal, reducing soreness, stiffness and fatigue after intense training.
- Supports cellular metabolism + repair, helping you recover faster between sessions.
- Reduces inflammation and discomfort associated with high‑load training and repetitive stress.
- Temperature‑regulating infrared fabric keeps you warm or cool as needed, ideal for all‑day wear.
The technology behind the textile
The science inside KYMIRA’s infrared performance baselayers
KYMIRA’s patented KYnergy® infrared textile embeds a matrix of bioceramic minerals into each fibre. These minerals capture body heat and convert it into far-infrared (FIR) light in the 6–14 µm range, supporting circulation, oxygenation, energy production and recovery.
How it works
From body heat to biological signalling, the technology is designed to support the body throughout movement and recovery.
Nitric oxide activation
FIR exposure is linked to increased nitric oxide availability, promoting local vasodilation and improved micro-circulation.
Enhanced oxygen delivery
Independent tcPO₂ studies show that FIR garments raise tissue oxygenation, supporting aerobic energy pathways at a lower physiological cost.
Mitochondrial efficiency
FIR supports cellular energy and ATP production, helping sustain output and reduce the sensation of fatigue.
Biological signalling
Exercise studies show FIR garments activate signalling pathways related to mitochondrial biogenesis and angiogenesis.
Thermal balance
FIR helps stabilise micro-temperature during and after exercise, while the textile maintains breathability and moisture management.
Why it matters for performance
Designed to support sustained output, movement quality and rapid in-session recovery.
Power, strength & endurance
- Improved oxygen delivery and faster aerobic system activation.
- More efficient ATP production and reduced oxygen consumption requirements.
- Support for sustained intensity, total work output and neuromuscular efficiency.
Movement quality
- Enhanced local circulation and oxygenation help prime muscles for movement.
- Support for mobility, flexibility, control and stability during high-speed movements.
- Greater acute skeletal muscle adaptive responses during exercise.
Rapid in-session recovery
- Supports the removal of fatiguing metabolites produced during exercise.
- Helps moderate soreness and inflammatory responses.
- Supports repair between efforts and training sessions.
Why KYMIRA supports injury prevention
Consistent movement starts with muscles that are prepared, oxygenated and able to maintain efficient mechanics under fatigue.
Enhanced circulation and oxygenation help prime muscles to be stronger and more flexible, supporting mobility and consistent movement patterns. Efficient muscular contraction, cellular energy support and reduced fatigue may help limit compensatory mechanics. Temperature regulation helps maintain muscle compliance, while recovery mechanisms support lower cumulative tissue stress between sessions.
Performance technologies should complement, not replace, a progressive training plan, appropriate warm-up, recovery, and professional medical advice where needed.
Size guide
The size charts below detail the relevant sizing or points of measurement for all of our products. Our garments do not need to be tight and against the skin for our infrared technology to work, so we suggest fitting to your personal preference. If you are looking for a looser fit, then size up from the guide's suggestions.
Unisex sizes
| Size | XS | S | M | L | XL | 2XL |
|---|---|---|---|---|---|---|
| K-Mask: Head circumference (UK only) | — | 45cm – 55cm | 50cm – 60cm | 55cm – 65cm | — | — |
| Socks & sleeves foot size (UK) | — | 3 – 5 | 6 – 8 | 9 – 11 | 14 – 16 | — |
| Socks & sleeves foot size (USA) | — | 5 – 6 | 7 – 10 | 11 – 14 | 15 – 17 | — |
| Socks & sleeves foot size (EU) | — | 35 – 38 | 39 – 42 | 43 – 47 | 49 – 52 | — |
| Socks & sleeves calf size (all) | 27cm – 32cm | 34cm – 39cm | 37cm – 42cm | 40cm – 45cm | 43cm – 48cm | 45cm – 50cm |
| Arm sleeves bicep size (all) | 26cm – 31cm | 29cm – 34cm | 32cm – 37cm | 35cm – 40cm | 38cm – 43cm | 42cm – 46cm |
Glove sizes
| Size | XS | S | M | L | XL |
|---|---|---|---|---|---|
| Gloves | 17cm | 17.5cm | 18cm | 18.5cm | 19cm |
| Gloves (when worn as a liner) | 17.5cm | 18cm | 18.5cm | 19cm | 20cm |
Women's sizes
| Size | XS | S | M | L | XL |
|---|---|---|---|---|---|
| Tops (chest, UK) | 8 | 10 | 12 | 14 | 16 |
| Leggings & shorts (waist, UK) | 8 | 10 | 12 | 14 | 16 |
| Tops (chest, USA) | 4 | 6 | 8 | 10 | 12 |
| Leggings & shorts (waist, USA) | 4 | 6 | 8 | 10 | 12 |
| Tops (chest, EU) | 36 | 38 | 40 | 42 | 44 |
| Leggings & shorts (waist, EU) | 36 | 38 | 40 | 42 | 44 |
Men's sizes
| Size | XS | S | M | L | XL | 2XL |
|---|---|---|---|---|---|---|
| Tops (chest) | 34" – 36" | 36" – 38" | 38" – 40" | 40" – 42" | 42" – 44" | 46" – 48" |
| Leggings & shorts (waist) | 28" | 30" | 32" | 34" | 36" | 38" |
| Leggings & shorts (inner leg) | 27" – 28" | 28" – 30" | 30" – 32" | 34" | 34" | 34" |
Trusted by elite athletes
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Frequently asked questions
Is my order tracked?
Absolutely. As soon as your vest leaves the warehouse, you will receive a shipping confirmation email containing a direct tracking link. You can follow your package's journey every step of the way right to your front door.
How much is shipping and how long does it take?
We offer simple shipping options for all mainland UK orders:
• Running Vests:
- Standard Shipping (3–4 Calendar Days): FREE
- Expedited Shipping (1–2 Calendar Days): £4.99
• Enertor Insoles:
- Standard Shipping (3–4 Calendar Days): FREE
- Expedited Shipping (1–2 Calendar Days): £5.04
• Socks (Partner Fulfilled):
- Standard Shipping (3–5 Working Days): £2.99
- Express Shipping (Tracked: 2–3 Working Days): £4.99
Order Processing & Cut-Off Times
• Cut-Off Time: Orders placed before 2:00 PM GMT are processed the same day. Orders placed after, or on UK Bank Holidays, will be processed the following day.
• 7-Day Delivery: Once dispatched, deliveries take place seven days a week, including Saturdays and Sundays. Please note that couriers do not deliver on official UK Bank Holidays, and these orders will arrive the next available day.
How Your Order is Fulfilled
To get your gear to you as fast and reliably as possible, we store our dedicated UK inventory within a premium professional fulfillment network managed by Amazon. Your running vests and insoles will arrive in high-quality, plain packaging to protect your unboxing experience. However, please don't be surprised if your tracking details or delivery courier are from Amazon Logistics—we use their world-class logistics to ensure your order hits your doorstep efficiently. Sock orders are fulfilled and dispatched directly by a partner brand.
What is the return policy?
Our goal is for every customer to be totally satisfied with their purchase. If this isn't the case, let us know and we'll do our best to work with you to make it right. You have 30 days from purchase to return a product due to an incorrect size ordered or to report a defect.
I want to ask a question...
Head to our contact page here, fill in the form and we'll get back to you within 24 hours.
Built To Last
Comes with a 2-Year Run With Freedom® Guarantee
Free Standard Shipping
Automatically applied at checkout with no minimum order required.
500ml Flask Included
Every vest comes equipped with a premium, taste-neutral soft flask made from eco-friendly materials.
Light Weight & Adjustable
Adjustable side straps and front straps for a great fit.
Secure Storage
Zipped pockets hold large phones & keys.
Rain or Shine
Whatever The Weather, Challenger is Ready.
2-Year Run With Freedom® Guarantee
We don't just talk about honest materials; we back them up. The Run With Freedom® Vest is built to withstand countless miles, season after season. That's why every vest is covered by our unconditional 2-Year Guarantee* against defects in materials and workmanship. This isn't just a warranty—it's a promise that your investment in speed and freedom is protected. Focus on your run, we'll focus on the gear.
Read more...*
Buckles & Hardware
Stitching & Seams
Fabric Integrity
Twin adjustable chest straps allow you to customise the tension on the fly, minimising vest movement and preventing chafing even when fully loaded.