IR “K” Series garments are loose, technical layering pieces that fit like a t-shirt, and the K2 long sleeve is the ‘midweight’ shirt in the line up. It’s also become the new favorite layering piece at IR. It’s made with a 7 oz Polaretec® PowerDry® polyester single-sided fleece with waffle grid texture on the inside. The fabric is only slightly heavier than a t-shirt, but the spaces in the grid trap heat and offer truly surprising warmth for such a light and supple fabric while offering great ventilation and breathability. We’ve been wearing these paddling, skiing and biking and in every case we have been delighted with how dry, warm and comfortable these shirts are.