Arc'teryx Small Bird Hat. Year-round performance on the mountain and off make this a go-to cap for trail runs, hikes, ski tours, and hanging out at camp. The classic ball cap design gets elevated with a technical stretch polyester plain weave material – the same structured mesh used in the Arc Konseal climbing harnesses – that breathes, stretches, and lasts. A Spacermesh™ headband helps manage moisture, and the adjustable back secures with a TPU strap and low-profile buckle.