Grab Tabs, or Traffic Handles, are a great little tool for when you don't need a leash dragging but want something to grab quickly and have your pup next to you in a pinch! Grab tabs are perfect for off leash activities that need to be on leash at some points, or even for indoor training! 
I didn't think much of this tool before making one for my foster dogs, who sometimes require a leash dragging in the house for quick control - I use it with new foster dogs who have graduated from the leash, and as a handle for my long-line with a D ring! I am a neat freak and hate touching a dirty handle!