The TUSA Fabric Mask Strap adds a new level of comfort to the dive experience. Anti-slip grip and easy adjustment ensures a snug fit to the back of the head. The snorkel keeper ensures secure placement. Features: Fits TUSA masks with the Swift Buckle 3D only. Easy size adjustment. Anti-slip on the back of the head. With snorkel holder. Head Circumference Size: 500-650mm. Material: Polyester and Nylon.