Raglan sleeves for easy movement Merino mesh underarm panels Flatlocked seams to prevent friction Thumb loops Ultimate warmth. Designed for the coldest days and the biggest adventure. Olympus is our warmest base layer offering unrivalled warmth to weight ratio and strategically placed mesh panels to ensure breathability. We use midweight 250 merino wool with added elastane so that Olympus will keep its shape and last longer.