For backpacking trips merino wool has been my first choice for many years as it doesn’t smell or feel sticky when worn day after day and always feels comfortable next to the skin. Rab mixes merino with recycled polyester treated with Cocona activated carbon, which comes from coconut shells. Cocona is said to increase the breathability of the polyester and speed up drying time. It also absorbs odours. I’ve used this top a great deal, including on two fortnightlong trips – a February traverse of the Southern Upland Way and the 2012 TGO Challenge – when it was worn every day and sometimes slept in and it has performed very well, feeling as comfortable at the end of trips as at the start. Drying time is quite fast. Hung up with a wet 100 per cent merino top of similar weight it does dry quicker though in actual use I haven’t noticed any significant difference. The Zip Tee has a high double fabric collar and a long zip for good ventilation. The cuffs are loose enough for the sleeves to be pushed up on hot days. The shoulder and side seams are offset to avoid wear from rucksack straps. All the seams are flat sewn. The fabric is quite thin and has proved comfortable to wear in warm weather, wicking sweat fast and not feeling sticky. Under other layers it works well in the cold too, making it suitable for year round use. The fabric has pilled slightly in places but not enough to matter other than cosmetically. The cut is described as ‘slim’. I’m usually a medium but Rab supplied a large size for test. The fabric has a slight one-way stretch so a medium might fit okay. As it is the slightly loose large size has been fine. Overall this top performs much like a 100 per cent merino one. It costs a little less than most zip neck merino garments.