With four way stretch and an 18" outseam for ultimate mobility, quick drying fabric, and a timeless silhouette, the Block Party Boardshorts 18" has been a staple in lineups for years â for more than a few reasons. Stock up for summer now. Features 94% polyester / 6% spandex with DWR coating. 18â outseam with straight leg. Block party stripes. Back pocket storage with velcro. Icon woven label. Imported.