Made of see thru netting with protected edges and hook and loop fasteners, these masks protect the llamas and alpaca eyes and face from pesky flies and gnats. Easy to attach and our llamas do not mind wearing them at all. We recommend removing at night and wash as needed. Xsmall for babies,, small for wealings, medium for yearling to average, large for larger adults and Xlarge for huge adults. (pictured on doll. this item does not have ear covers as llamas and alpacas do not tolerate ear covers well) To meausre for size go by halter size or measure around the nose where a halter would fit. small 12-14" medium 14-16" larege 16-18" and XL 18-20"