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Quantity
1
Our Altitude range was originally designed as a baselayer, to fit close to your body for maximum performance, so it’s snug but soft, with plenty of give for extra comfort. If you’re usually a medium, for example, you might find the medium ...
Reviews
4.8
48 ratings
5
4
3
2
1
So happy!
First I bought 2, then I bought 2 more. I am a runner, and I am always cold in between, so I live in skivvies all winter. I'm replacing them all with these tops- they are warm, snug on the body, super flattering, love the extra length that doesn't let any draughts in from the bottom. Great customer service too, 2 of the tops had some stitching issues and it couldn't have been easier to get them replaced. Will definitely buy more! Im a pretty standard M, and went with that size, and they are perfect.
M
M. · April 22, 2026
Excellent
Neat fit. Appreciate sleeve and body length being a little longer than strictly necessary - longer by 2 cm than my existing ioMerino, much-worn, collared tops.
Kath. (165 cm, 52 kg)
K
Kath · November 17, 2025
Perfect every time
This is my third purchase from IO. I love their high quality, warm, long-lasting tops. I am normally a small but medium fits me best with IO. I wouldn't buy any other brand.The service is absolutely perfect every time too.
