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men'S tops

Runterra Bio Tee

M's Runterra Bio Tee

Heads up, this gear will ship in 3-5 weeks. Learn more about pre-orders.


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run everywhere guarantee
free shipping over $50
free 60 day exchanges
William is 6'1" and wears size M Aron is 5'11" and wears size M Regular fit, Size Chart

Run in it, sweat in it, live in it — then biodegrade it!

The first synthetic-blend running shirt that biodegrades like a 100% cotton tee, our Runterra Bio offers the enhanced moisture and odor control of specially-formulated 37.5® polyester with the comfort and versatility of cotton. This new, innovative fabric breaks down into organic compounds in under four years. Conventional polyester takes four hundred.

Don’t sweat it  this tee will only start to biodegrade in anaerobic (oxygen-poor) environments. It breaks down in the landfill, not in your closet.

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Runterra Bio is powered by a specially formulated 37.5® polyester with enhanced biodegradation to break down into bio-based compounds in under 4 years in an oxygen-poor environment like a landfill

Premium cotton
Made from long staple, US-grown Supima® cotton for superior softness, strength + durability

Everyday looks
Easy to wear, casual cut with a straight hemline

Active comfort
Blended with 37.5® polyester, a special technology utilizing the natural benefits of microscopic volcanic ash to provide enhanced thermal, vapor + odor regulation to maintain body comfort during activity

Wear more, wash less
The natural odor resistance of cotton is boosted by the volcanic particles which "trap" odors so you can put this top through repeated wear

Modified raglan design
Shoulder seams are rolled back off the top of the shoulders for ergonomic comfort

Hang it up
An elastic locker loop is integrated into the back neck tape for easy hanging

Shrinkage is natural
This top is made from 70% natural fibers and is not pre-shrunk so some shrinkage may occur, up to half a size

materials + specs

70% Supima® cotton, 30% 37.5® tech polyester

Garment made in Vietnam

103g / 3.6oz (M’s Medium)"

Fabric Callout


Lightweight, resilient, and versatile, Runterra wears like your softest cotton tee with the added benefits of active odor-resistance and thermoregulation — thanks to volcanic particles embedded within the fabric.


care instructions

Wash cold with like colors

Machine dry low or hang dry for best results and lifespan of the garment

Heads up — Runterra is not pre-shrunk

We have relaxed the body and slightly lengthened the sleeves of this top to accommodate for some shrinkage which may occur in the wash cycle since Runterra is made from a majority natural fiber.

Avoid washing and drying with high heat.


Why do biodegradable synthetics matter? 

While we design Janji gear to last and hold up to the demand of years of running, no tee or running shorts should last forever. With this in mind, we are researching innovative ways to improve end-of-life cycle management of our apparel. While we look into longer-term solutions and circular methods — recycle, repurpose and reuse programs — we also know that most textiles are thrown out and end up in landfills. Conventional synthetics, used heavily in active apparel for their high-performance functionality, do not biodegrade in typical landfill conditions. This includes synthetics made from recycled materials, and is why most plastic seemingly lasts forever.

We are seeking solutions to fix this as a performance apparel company that relies on synthetics, including the use of non-ecotoxic biodegradability within our textiles like this new Runterra Bio. This is the first step on a better path forward.

Runterra is made from premium, long-staple Supima® cotton which is 50% longer and up to 45% stronger than other cottons (and softer, too). The stronger the fiber, the more durable the garment, and therefore the more it can be worn. Supima® cotton is grown by a select few family farms that utilize advanced water and soil management techniques to reduce consumption and ensure the health of the land for optimal renewability.

Runterra fabric is also OEKO-TEX® certified, meaning it is free from harmful chemicals and is fabricated in a way that meets a high environmental standard.

Learn more about our sustainable initiatives here.


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Customer Reviews

Based on 15 reviews
Andy Gluck
Wear it for: Running, Hiking
Product Fit: Spot-on
Height: 5'4" to 5'6"
Usual Size: M
Size Purchased: M
Comfy T

What a versatile T! Great for a workout, day wear or evening shirt.
Light and comfy.

Brendan Moore
Wear it for: Running
Product Fit: Runs small
Height: 5'10" to 6'0"
Usual Size: M
Size Purchased: S
Good shirt!

Really nice shirt. I got the orange one. I'm 5'10 160 lbs male and I always choose S or M shirts and I choose small which was too tight. I wish I picked a medium. Good shirts for runs/hiking.

Gerik T.
Wear it for: Running
Product Fit: Spot-on
Height: 6'3" or taller
Usual Size: M
Size Purchased: M
Amazing shirts

I have 6 Janji short sleeves and these are by far the comfiest shirts I've bought in my life. I pretty much wear my shirts every day for the past 5 months and no signs of pilling or wear. Medium fits me perfectly as a 6'3 175 guy.

Kiernon Murray
love it

great shirt!


My favorite shirt. I’ve got it in three colors and wear them on every run. They’re breathable, move seamlessly, and are incredibly comfortable.

LOVE- Abrasive backing for long runs

Love this shirt super comfortable. Only complaint comes on longer runs when the backing from the image (on front of shirt only back is not a problem)- starts to be abrasive to the skin and caused some chaffing on my chest. Otherwise this shirt material and style ROCK, and I would recommend it to anyone.
In the future solutions to the chaffing issue could be:
1. Janji removes the logo from the front during production
2. I need to put some body glide on my chest or only use for shorter runs
3. quit whining and RUN :)

love the new fit

very strong new fit, especially after the wash. enjoy it and doesnt seem to smell, which is great

Rajan Singh
Love it

It's a great running shirt, not much else to say

Great running tee

Lightweight and comfy, good fit, and you really can wear it more than once!

Stephen Eginoire
My favorite shirt

This is my new favorite shirt. I love the material and the construction is awesome. As an artist myself, I'm really into the font/design elements.