The Vex is a lightweight, effective chest protector offering protection in any riding situation. Lightweight, durable polycarbonate construction. Ventilated design for maximum breathability. Low-profile, lightweight design. Full chest and spine coverage. Adjustable front and back panels. Neck brace compatible design. Sizing: Small: Under 75 pounds. Medium: 75 - 140 pounds. Large: 140 - 190 pounds.