This Mac Retractable Dog Leash is for large dogs. Its retractable belt extends up to 21 feet. The Max retractable is designed for walking your dog in open areas where they can enjoy lots of extra "freedom on the leash". Mac retractable leashes are known for their high-quality, superior durability and attractive design. The one-thumb braking and recoil system allows you to maintain full control of your dog during your walks together. This innovative system is integrated into the leash"s ergonomic handle so it"s easy to adjust the leash to an appropriate length for your surroundings. The lock button allows the leash to stay at a constant length.To release break lock,simpily press the break button with your thumb,draw back the lock,and slowly release the break button.