Spere Pant Men's Arc'teryx United States Spere Pant Men's Arc'teryx United States Spere Pant Men's Arc'teryx Spere Pant Men's Arc'teryx. Elegant and visually interesting, the Serpens have a snake like style line along its wide leg. This ankle length trouser is cut in a soft crinkle cotton, ideal for the front pleats and draped, classic silhouette. As always, comfort and functionality are assured by the elastic inserts at the waistband and slanted pockets. 100% Cotton. Available in Raspberry or Sand. Sizes XS XXL. Katia is 55 and wears a size XS (Black). Marie is 56 and wears a size XS (Raspberry & Sand). Machine wash in cold water. Hang to dry. Ethically made in Montreal, Canada.