The CLIX Recall Line allows the dog to be seemingly free and yet remain under control. An essential tool for recall training and ideal to allow controlled socialisation for puppies and young dogs.
If you're often road walking, then a fixed length lead is recommended to help keep your dog close by. If you're not, but your dog isn't so responsive to recall, then a retractable lead is best for you.
 
As a general rule, keep your dog on a lead if you cannot rely on its obedience. On a bridleway or byway this is especially important as you may meet horses or other dogs.