FINIS Swim Posture Trainer Promotes correct head and spine alignment, which is key to an efficient swim stroke. Can be used for all four swim strokes: butterfly, backstroke, breaststroke and freestyle. Secures to the back center of the head, and should be undetectable until the swimmer exceeds the recommended posture range. Can be worn with or without goggles, one size fits all. Made of durable HDPE plastic that is chlorine and UV resistant. USA PATENTED US 9,586,118 B2