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Altitude Zip

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Dark Khaki
Moroccan Blue
Charcoal Marle
Dark Blue Marle

Our Altitude range is designed to fit close to your body for maximum performance, so it’s tight but still soft, with plenty of give for extra comfort. The Men’s Altitude Zip Base Layer thermal takes natural temperature regulation to a whole new level. It is the perfect ‘go to’ thermal layer for just about any adventure, especially if you’re expecting to hit a range of temperatures. 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 Men'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.

This Base Layer Thermal top is the perfect combination of performance, warmth and comfort.

(For a more relaxed fit try our Ultra Zip.)

Ultra Trail Australia mandatory gear approved thermals.

Designed to be worn as a body tight ‘contact fit’ layer. 

Drop back hem and extra length in body. 

Thumb loops.

Zip Neck.

True to size. 

Model wears size medium in Moroccan blue and green.
Model wears size small in rust.
Model specs - height 181cm, chest 103cm, waist 81cm.

Model wears small in Charcoal marle and black.
Model specs - height 173, chest 99cm, waist 76cm.

Model is 6'2" and wears size large in Dark blue marle. 
Model specs - height 173, chest 99cm, waist 76cm.

Size Guide. Contact Fit.

Snow Sports



170gsm lightweight

96% superfine Australian Merino

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

MicroMerino®  Fabric. 










Customer Reviews

Based on 42 reviews
Ben Lyons (Toowoomba, AU)
Another great Merino product

Have been a long time user of merino products from ioMerino right from the early days and I am so glad to see them hanging in there and providing updated fantastic clothing. I use the base and mid layers all year round for golf, walking and exercise. Wish I could buy more. I still have ioMerino shirts from over ten years ago - amazing stamina!

Andrew Driscall (Melbourne, AU)
Can’t fault it

I find myself virtually living in it full time.

Lord Remi (Melbourne, AU)

It's the best base layer I have, I've got several kinds but it's my favorite, I've bought two of them 10 years ago in Quebec. Unable to find any more, I made the purchase in Australia and I am still satisfied with the 2022 version.

Chris Halstead (Adelaide CBD, AU)

Great product works well for sea kayaking

Pero (North Vancouver, CA)
So comfortable

I have been wearing IoMerino for probably 15 years now, even going way when it IO BIO. The quality is top notch, and softer and better then the other top competitors. Unfortunately there isn't a Canadian distributor anymore, but that didn't stop me from still purchasing online and shipping here to Vancouver, Sizing is true .with the duty and taxes its a little more, but well worth it my opinion. The Altitude Zip is my favorite, it hugs the body so well, and regulates the heat, and colors are vibrant. During my winter rides when its down to 5c I wear the altitude, pinnacle Zip, and altitude neck tub with a high Vis wind stopping and its perfect. Overall I love the product line, and have many different pieces! The customer support is fantastic as well!

Cass (Melbourne, AU)
Altitude Zip - Recommendable

This is my second Altitude Zip. What I like: the soft feel, the fit, the high neck, a choice of colours, the quick delivery. It really has a remarkably soft feel, and I enjoy putting it one each time I wear it. I use it in combination with a roll neck jumper in cooler weather, and really appreciate the way the higher-than-average neck keeps me warm, and keeps the coarser wool of the jumper off my neck. I found it 'true to size', ie the 'Large' size fitted me as I expected. It was good to get some colour options, rather than black-or-nothing. I received the item a day or two after I placed the order (and the website was well organised). I can live without the thumb holes, but others will appreciate them, and they don't get in my way. A classy product, and recommendable!