Cheerleader Dress up Halloween Costume Outfit for Dog- MEDIUM Velcro Closure on underside of neck and belly for slightly adjustable fit. 100% Polyester Size is MEDIUM. ACTUAL MEASUREMENTS (laid flat): Back Length: 12.5", Neck Girth: 12", Chest Girth: 16". For length measure from base of neck to base of tail. For neck & chest measurements be sure to measure width around widest points of neck & belly.