Because your children have ideal freedom of arm movement here, unlike with conventional swim wings. The snug neoprene material is very comfortable to wear, and especially in cool water, your children will appreciate the pleasant warmth that this jacket provides. The jacket includes several pockets containing the buoyancy material. You can remove these blocks individually, allowing you to optimally adjust the buoyancy of the swim jacket to your child's swimming ability. The swim aid keeps your child in a vertical position and above the water. The back is bright yellow, ensuring that you can see your child immediately.