"The Big Dog Halter is designed specifically for large breed dogs who are aggressive leash pullers! It is guaranteed to stop your dog from pulling using the patented ""Sporn Effect"". It's easily transformed into a standard collar when the pull-control function is not needed. All materials and components are made of the highest quality nylon and nickel-plated hardware to reduce weathering. FEATURES:Great for leash trainingStops pulling instantlyReflective restraints for safetyPadded underarm restraints for comfortHand washableLifetime guarantee (excludes chewing)Available in 3 sizesSizing Recommendations:Medium 35.5-48cm (14-19 inch)  neck  and approximately 11-27kg (25-60 pounds)Large 35.5cm -60cm (19-24 inch)  neck and approximately 27-45kg (60-100 pounds)Extra Large 60-83cm (24-33 inch) neck and approximately 45-68kg (100-150 pounds) WARNING: Do not leave halter on dog unattended. Not to be used as a tie-out or car harness."