Equipement Safety Backup 
 
Choose a color from the list of paracrd. These are designed with a clasp on both ends. The length is about 7-8" (including the clasps). 
 
These are not meant for excessive pulling. They are meant to be a backup incase a collar (or any other equipement) fails, to give you a few seconds to reattach your dog to the proper equipement. 
 
For example, we attach ours to the leash and their regular collar or harness, while wearing a prong collar. We've had prong collars accidently pop off and this kept the leash still attached to our dog via their regular collar.