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Altitude 'Mongrel' Zip

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Gothic Grape

You know our world famous, best selling Mongrel top? Well this is the zip version of it. Just like the regular one, this is a bit of fun, super limited edition because it's made from bits and pieces of this season's colours, and a seriously good thermal Base Layer. Or a seriously good top for running or hiking or drinking that latte or whatever else you want to do in it.

The perfect combination of performance, warmth and comfort with a little bit of fun thrown in for good measure.  

Zip down when it’s mild, zip up and thumb loops on when the temperature drops.  The high collar also offers an extra level of warmth beyond the Women's Altitude Crew Neck Base Layer version of this top.

Flatlock stitching, raglan sleeves and tag free to eliminate chafe and maximize comfort. The drop back hem and extra body length is designed for tucking into your outer layers. Thumb loops keep your hands warm and stop your sleeves riding up when layering. 

Ultra Trail Australia mandatory gear approved thermals

Why you’d buy this: You like your stuff to fit nice and close to your body whether you wear it on its own, or under another layer and don’t want any extra bulk or bunching. You might also want a bit of extra length which this one gives you. It’s super soft and comfy, and 96% merino so it’s super natural which means almost no microplastic issues when you wash it or landfill when you’ve finished with it.

As with all our clothes, the merino delivers natural temperature regulation, breathability, moisture wicking and odour resistance.

Designed to be worn as a body tight ‘contact fit’ layer. Slightly looser than the Altitude long sleeve styles.

Drop back hem and extra length in body. 

Thumb loops. 

Model wears size Medium.

Size Guide. Contact Fit.

Snow sports



170gsm lightweight

96% superfine Australian Merino

4% Elastane - for an easy all-way stretch.

A MicroMerino® Fabric.










Customer Reviews

Based on 9 reviews
Brodribb Penny (Melbourne, AU)
Great colours but very thin

The mongrel in my second io merino purchase. I love the colours and the cut but like my previous top it is very thin perhaps even thinner than my last one which fell apart within a year. I don't expect this one to last long either and the elastane blend means I can't put it in the worm farm when it's dead.
It certainly looks fantastic and I've had heaps of positive comments but probably won't buy from iO again unless they are heavily reduced as doesn't seem lime good value.

Hi Penny,
Given how unhappy you are, three stars is probably not a bad review so thanks for that. But we’d actually like to find out more about what’s gone wrong with your original mongrel. Our natural fabric won’t last forever like synthetics, (which is one of the GOOD things about them!), but they should definitely be lasting you longer than 12 months, so if you can reach out to customer service we’d love to have a chat and see if we can work out what the problem was and if there’s anything we can do to help. (It’s also worth mentioning the new Mongrels are made out of our usual fabrics so shouldn’t be any thinner, and while they are a definitely a relatively lightweight fabric, they’re designed that way and punch well above their weight when it comes to warmth.) Please contact hello@io-merino.com and we look forward to hearing from you.

Just love it.

I love this shirt. I read previous reviews about sizing I normally wear medium sometimes large, I chose XL. I may have been ok with the large but I will take comfort over a size label any day. It’s very comfy, the natural fibre helps regulate my body heat., plus I get lots of compliments. It’s great quality, I am very happy with this purchase.
I spoke to a person over the phone and they couldn’t have been more helpful. I don’t think I’ll be buying that other brand anymore.


Sensational! Very comfie and looks amazing with the colour combo. I love the length of these shirts. Long enough for my backpack to not ride up, but also doesn’t bunch up. I now have 4x of the mongrels.


Love my new " Mongrel" zip up so much that I ordered another one immediately so that I have a reserve.
Super comfy and I wore it for days without it smelling. Easy to wash and dry and the design and colour combination are exactly to my taste! Great quality products!

Jenny (Sydney, AU)
Great eye catching colours

Love the colours, it’s a snug fit (medium I’m at 12 Aussie) , so good for layering, a little see through but ok

Lorill Jensen (Kelowna, CA)
Fits small

I ordered the XLand it is tight. I normally wear a Large, never an XL.

I would say in Canadian sizes, it is more like a medium or large slim fit. Not very flattering if you have any love handles. It is cute and I hope I can lose enough weight to wear it one day.