Your Cart is Empty

Ultra Zip is Ultra Versatile and Cosy

September 01, 2021

Woman in the snow wearing ioMerino outdoor clothing

(NOTE: This is an actual customer review we received recently. We didn't ask for anyone to write it. They were not paid to write it. They just liked their top so much they wrote it so here it is, in their own words. Not us telling you how good our stuff is, but a fellow Outsider.)

The Ultra Zip has the best all around fit for comfort, function, performance and durability that I have found when compared to other brands and styles of wool tops. I found that the true to size recommendation is spot on. I typically wear a medium shirt and the medium fits great. Approx. 5'10", 40" chest, 33" waist. If you are like me and don't like garments that are too snug around the arm pits then you will love the Ultra Zip.

Men's merino wool charcoal ultra zip Women's merino wool silver pine ulta zip

Even when I put my work shirt over the Ultra I don't get bunching or that restricted feeling under the arm pit. It still has a mild form fitment that tends to lay on the body but doesn't squeeze the body so it is not restrictive in any way. This perfect balance between fitment and comfort will allow you to wear the Ultra Zip as a base layer if you like and still allow full range of motion under casual or more dressy shirts as well as any other type of mid layer without bunching or discomfort of any kind, even when wearing a cotton shirt or fleece jacket over the Ultra.

Check out the men's ultra versatile Ultra Zip
And here's the women's ultra comfortable Ultra Zip

Women's merino wool ultra zip in red Men's merino wool ultra zip in blue

The Ultra's fabric weight of 160 GSM has the best balance of temperature regulation and warmth to weight ratio for my body's temperature temperament. I get cold easily but when I start to heat up the heat builds fast. I need a comfortable lightweight layer that reasonably resists the cool and breaths fast when needed; io did just that with the Ultra. I love how the superfine wool resists heat loss when mostly static but once you start to heat up it allows quick ventilation.

The sleeves can also be worn comfortably when pushed up the arm past the elbow due to the really good stretch that the elastane offers and it has no issues repeatedly returning back to its original shape after the garment has been stretched. It is absolutely true that lightweight wool of this nature will benefit from the addition of a small percentage of nylon. I encourage you to look up all the benefits. No need for me to bore ya in this review but suffice it to say that while the site does mention you can poke your finger through the wool especially when wet (listed in io's section of top 7 things of What Not To Do) if you're not careful, when nylon is added to the fabric recipe it exponentially reduces accidents like this from happening.

Men's merino wool ultra zip in grey Women's merino wool ultra zip in blue Women's merino wool ultra zip in charcoal

Nylon is also less prone to shrinking so if you do need to throw the Ultra in the dryer on low or very low heat it helps to resist any heat related shrinkage. I have thrown the Ultra in the dryer many times with perfect success but I don't let the dryer completely dry out the fabric. I use this same principal on many of my clothes and all of my wool garments with no negative issues to date and I have been doing this for over 20 years with perfect success; but, your specific conditions and equipment's ability to maintain proper temperature reliably could differ. If you choose to use the dryer, I highly advise to check your dryer very often until you are 100% confident and familiar with your equipment's performance to ensure no over-drying of the fabric occurs.

From daily wear, athletic activities to cosy bed time comfort, I have not yet found a limit for the Ultra. The Ultra Zip may just be the Ultimate all around versatile and cosy top you can find. :O) I highly recommend this product.

Thadiusmaximus (The Villages, US)

If you haven't already, take a look at our highly recommended men's and women's Ultra Zips right here!


How To Choose Your Next Race
How To Choose Your Next Race

May 29, 2022

With so many events now on the running calendar, we asked Outsider Sputnik for his best tips on how to choose events when you can’t do them all.
Read More
Group of trail runners outdoors
Get Race Ready

March 18, 2022

Race season is kicking off. And with any luck, this year we’ll have a bunch of actual races. In the real world. With other people. Boom! So it’s time to get ready to go.
Read More
Where do you want to go with io?
Where do you want to go with io?

March 04, 2022

Simply tell us in 20 words or less where you want to go right now and why, to be in with the chance to win one of two $100 ioMerino vouchers. 
Read More


Fabric Guide

While Merino is an amazing natural fibre, not all Merino fabrics are created equal. At ioMerino, we make our own fabrics, using only the best quality fibres, and to very specific specifications that make the most of the natural benefits of Merino. All of them are 'Merino rich’. No cheap blends passed off as Merino. No cheaper scratchy fibres or synthetic substitutes to save money. No unethical production. And each fabric is made for a specific purpose. So if you see something with a small amount of elastase or nylon added, you can be sure it absolutely needs to be there to enhance the natural stretch and durability. 

It took every bit of our 140 years of experience in the wool industry to perfect our fabrics, but we think you’ll agree the end result was more than worth the effort.

Ethically Made. Ethically Sourced. Perfectly Natural. 


Altitude / Zodiac

Lightweight 170gsm 96% Australian Merino Wool with 4% elastane for extra stretch and comfort. A MicroMerino® Fabric. 


Ultra / Universal

Lightweight 160gsm 83% Australian Merino Wool blended with 12% nylon blended for extra durability and 5% Elastane for stretch and comfort.



Midweight 265gsm 96% Australian Merino Wool with 4% elastane for extra stretch and comfort. A MicroMerino® Fabric. 


Summerino - Celsius 

Made from 45% ultra fine MERINO (Ultra Lightweight 150gsm), 45% natural TENCEL (made from sustainably grown wood fiber), and 10% nylon for extra durability. 


Summerino - Keystone 

Ultra Lightweight 150gsm 100% Australian Merino Wool. A MicroMerino® Fabric. 


Merino Compression

Midweight 280gsm 76% Australian Merino Wool, 15% Elastane and 9% Nylon for extra stretch and compression properties.



Ultra lightweight ribbed 155gsm 100% Australian Merino Wool. A MicroMerino®  Fabric. 



Outer Weight 280gsm Fleece 100% Australian Merino Wool. MicroMerino®  Fabric. 



Midweight 260gsm 100% Australian Merino Wool. A MicroMerino®  Fabric. 



Midweight 260gsm waffle texture 100% Australian Merino Wool. A MicroMerino®  Fabric. 


Stride / Glacier / Velocity

Midweight 255gsm French Terry 100% Australian Merino Wool. A MicroMerino®  Fabric. 


Natural Merino Wool benefits: